path: root/2022/captions/emacsconf-2022-realestate--real-estate-and-org-table-formulas--daniel-gopar--main.vtt

WEBVTT captioned by tom


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Hey, I'm Gopar and this is the

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Real Estate and Org Mode Table Formulas talk.

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Not very creative, but it is what it is.

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Now I just want to say that everything I talk about here

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is in the Org Mode in the Emacs manual.

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I posted a link to the web version,

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but it should be inside of Emacs as well.

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Now before I start, I want to showcase the end goal.

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That way you know if you guys want to

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actually see the talk or not.

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So I always think that's pretty cool to see

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what you're actually going to build

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before you start building it.

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Alright. So let me start off with the goal,

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the end goal. Here we have a simple table formula

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and we have some constants, some values inside the list--

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inside the table, I'm sorry,

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and some other stuff that we will get to,

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but for now... I don't want to spoil too much.

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I just want to give you a demo

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of how it actually works.

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We have a few values. Let me first go over the constants.

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We have PMI, which stands for

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private mortgage insurance,

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so it's insurance that you'll have to pay

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depending on how much money you put into the deal.

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The property tax, which is self-explanatory,

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the tax that you owe for owning the property,

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and then home insurance,

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and the interest rate at the loan that you get.

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So, here we have a few columns.

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The first one is called House,

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which I usually just put a description of the house

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with the link of the posting,

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the price of the house,

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the percentage down payment (this I play around with

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to see how much the deal will be structured),

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the down payment (which is calculated from

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the previous two columns),

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the monthly mortgage (which is calculated as well),

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and then the tenant income (which is what I suppose

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would be an example of the tenant income

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that I can potentially make off the property,

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the 1% rule and the ROI.

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I'll quickly go over the last two columns.

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So first is the 1% rule.

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The 1% rule is essentially

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a "rule," in quotes, that says that

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if a property matches this specific formula,

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it is a good deal to look into.

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So for example, the first two pass,

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and the last one does not pass.

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The last one, at a quick glance,

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we can just ignore it and say,

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"hey, that's not going to fly,"

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we'll just ignore it.

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I won't go too much into details.

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That's just a brief summary.

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So now the ROI is the return on investment.

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So it says "how much of a return am I getting

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on the amount that I invested?"

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So let's say you put in $12,000,

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and at the end of the year, you cashflow $6,000.

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So if you calculate the ROI off of that,

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you get a 50% return on investment.

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In two years, you'll make your money back,

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which is pretty good.

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Then all the rest of the years,

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you'll just slowly be reaping in all that,

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all the excess cash flow.

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But yeah, that's it in a nutshell.

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So let me demo it real quick.

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So for example, I'm going to change the down payment,

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but I want you to pay attention

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to this column [down payment]

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and the monthly mortgage column.

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So right here [down payment] is $25,000,

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and here [monthly mortgage] is around $1,200,

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a little under $1,300.

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So what happens if I say, you know,

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what I'm going to change the down payment

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to 5% instead, because I just

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don't want to put 10.

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So let's just put say 5.

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Then I tab out of here, and voila -

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you see it updated to half of $25,000.

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So now it's $12,000,

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and this [monthly mortgage] went up

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over actually $1,300,

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and then this [1% rule] hasn't changed at all

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and the ROI is there.

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So one thing that I should mention is

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everything that I'm putting here

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is just example numbers,

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should not be taken into literal real estate advice.

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I just want to put that out there.

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These are just examples to show you

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how you can potentially make it on your own,

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do the formulas on your own.

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Alright, so another cool thing that I did was

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if there is no tenant income and I tab,

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it says "Enter Tenant Income".

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So if I don't put anything,

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it will automatically tell me, hey,

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I can't calculate without the tenant income.

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I can also do this right here [ROI field],

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say the same thing, Enter Tenant Income,

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but I just didn't put it for whatever reason, but

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after this video, you should be easily able to

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put it without much struggle.

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Alright, so if that's something you're interested in,

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then keep watching.

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So let's go over the basics first.

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So, how do we create a table?

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Well, we can do M-x org-table-create.

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If we run that it, will prompt us in a minibuffer.

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It says table size, columns times row.

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Usually it's rows times columns,

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but it is what it is.

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So let's just leave

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the default of 5 times 2, and voila, we get this.

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Beautiful. Awesome.

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So the other way is using the magical C-c C-c

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in Org Mode, which basically is context-aware

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and does anything, does the right thing like,

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almost 100% of the time, which is pretty amazing.

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Alright, let's just say I write a pipe, some words,

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and then another pipe, Gopar, and then

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another pipe. Let's just say we're trying to

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write it out via text, because in Org mode

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everything has text.

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There's nothing fancy about it.

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If I do C-c C-c, Org mode should automatically be

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context-aware that this area is a table.

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So, C-c C-c, boom. So if I press enter, another column.

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If I press tab, it should automatically move me.

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So yeah, so that's pretty much it.

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That's how you get started into the column.

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So, I'm assuming most of the people here already know that.

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This is just the primary basic review.

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So, let's first go...

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Let's go dive right into our first formula.

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So I copied some values over here,

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just to save time, and the columns.

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So, let's go ahead and say that

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we have single family house,

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and the price is a hundred thousand.

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And, Let's say that I want the price,

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the down payment that I want to put is 10%.

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Right. Alright. 10%. Now if I tab

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or go to the next column, nothing happens.

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Why is that? Well, it's because

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(you probably guessed it)

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we haven't written or tied any table formulas.

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So we're saying, alright, enough talk.

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How do we do that?

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Well, the answer is very simple.

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We do a pound sign (#), if I can find it.

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#+ and then we do TBL for table

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and then FM for formula.

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So, table formula, and the column.

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So this, you're already halfway

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to writing your first table formula.

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So let's say we want to automatically,

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Let's just, for exercise,

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we want to put the down payment,

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just put some type of value in there,

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just to make sure that it's working.

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So the way Org Mode refers to columns is,

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we start with the dollar sign ($) and then

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we put the number that the column is.

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Indexes start with one, not a zero.

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As most of us watching are programmers,

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we're probably used to starting with zero,

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but it starts with one.

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So one, two, three, four, five.

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So down payment is the fifth column,

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we say five, and then we say equal to,

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let's say Gopar.

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Then we do C-c C-c to evaluate it,

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and the table is automatically updated.

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Look at that.

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So when you do just this, dollar sign ($) 5,

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it updates every single column.

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There is a way to specify that this cell only and

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this cell only but this is out of scope and it's

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not that hard it's just not in this video.

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I would recommend, I commend you, or, actually

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I recommend that you go check out the manual for that.

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All right so, let's say we want to do some basic

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arithmetic we want to do some list values

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instead of just putting in text.

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So how do we do that?

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Well, we have to pull the expression that we want

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to put in.

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So, for example, if we want to add we'll do 20 plus

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20 and if we do C-c C-C to evaluate it, it should

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update every single column, the entire column,

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the fifth column I mean and, tada, it does.

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Cool! So now let's say we want to do a little bit

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more advanced.

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Let's say we want to add the previous column to

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this column, so how do we refer to this one?

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Well, 1-2-3-4 is the fourth column, so we would

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just simply do $4 and this should automatically

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be referring to this column (% DP).

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So we'll do 10 + 20, it's going to be 30 over here,

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and let's do C-C C-c.

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Ooh, error, what happened?

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Oh my god, oh my god.

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Well, this seems scary but no worries.

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This is where debugging comes in pretty handy,

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which is actually our next section as you can see.

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So, what happens if we do, if we go into the

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debugging section, what is the first step?

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Well, the first step is to try out, is to enable

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formula debugger.

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So, if you do C-c {, it will turn on a minor mode

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that whenever you evaluate a table formula,

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the debugger will be enabled,

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will automatically kick in.

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And if you want to disable the debugger,

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you just run the command again, and it will turn off.

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So, let's go ahead and run it. C-c {.

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As you can see in the mini buffer, it says,

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"formula debugging has been turned on". Awesome!

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So if we go back to our table

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and we try to run this, and see what's going on, we see...

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Oh, first off, before we look

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at the buffer that just opened,

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look at the mini buffer,

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it says "Debugging Formula. Continue to next?"

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So if you have multiple or a series of formulas,

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it will say, "hey, do you want to debug this one

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or the next one?"

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So this is just saying, "hey, do you want to go

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into the next formula?"

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And since there's no next formula,

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debugger will just exit out

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and leave you with the other buffer to see.

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For now, we'll just click no.

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Right now, it doesn't matter if you click yes or no

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because there's only one formula,

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but we'll just click no, and let's go ahead and

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pay attention to the new buffer.

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Well, over here it might seem a little confusing,

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but don't worry, we're just going to ignore most of this.

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The first thing that we're going to pay

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attention is to the original.

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So it says, okay, this is the original, so we have

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a quote expression, which is just trying to add the

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fourth column.

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And if we go over here

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once everything is finalized,

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it says "hey, we're trying to add this 10,

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but it's actually a string 10, and added to 20.

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So of course it's going to be an error, so now we

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know what the error is.

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So you're saying all right cool, awesome, now how

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do we transform that string into a number?

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Well, Org Mode formulas have these flags

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that you can use, and essentially a flag looks like this.

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It's a semicolon (;) followed by some letter

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or some identifier

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that will let Org mode know that hey,

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this should be turned into a number

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or this should be turned into whatever.

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There's different ones for alpha literal

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and for a bunch of...

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I think there's even "i" for "integer",

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so it depends what you want.

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So for now we're just going to put "number"

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because it's a real number.

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If we do this and the debugger is still on,

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(remember because it automatically

00:10:35.374 --> 00:10:36.374
stays on until we turn it off),

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if we reevaluate the the formula,

00:10:41.640 --> 00:10:43.624
we should be able to see it.

00:10:43.724 --> 00:10:47.379
But first, before I do that, let's check step two.

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I'll now rerun formulas with C-c * and table,

00:10:52.340 --> 00:10:54.639
which calls org-table-recalculate.

00:10:54.640 --> 00:10:58.507
To do this, you actually have to be inside the table.

00:10:58.607 --> 00:11:02.354
Otherwise, Org mode will try to do some other stuff

00:11:02.454 --> 00:11:04.325
because it is context-aware, so depending on

00:11:04.425 --> 00:11:06.324
the context it might do something else.

00:11:06.424 --> 00:11:09.124
So if we do C-c *...

00:11:09.224 --> 00:11:12.724
As you can see the debugger has kicked in,

00:11:12.824 --> 00:11:14.102
says, "Do you want to continue to next?"

00:11:14.202 --> 00:11:17.580
Let's press yes (y), and it has been applied.

00:11:17.680 --> 00:11:20.971
So as you can see, it only updated one column--

00:11:21.071 --> 00:11:22.977
I'm sorry, one row--and the thing is,

00:11:23.077 --> 00:11:28.007
when you run this, the recalculate, it will only

00:11:28.107 --> 00:11:30.361
run for the current row that you're in.

00:11:30.461 --> 00:11:32.785
If you want to run for the entire table,

00:11:32.885 --> 00:11:36.240
you're going to do C-u C-c *.

00:11:36.340 --> 00:11:38.407
Before I do that, let me turn off the debugger

00:11:38.507 --> 00:11:40.807
since we no longer are in need of it.

00:11:40.907 --> 00:11:44.977
So C-c {, and debugging has been turned off.

00:11:45.077 --> 00:11:50.807
Now let me do C-u C-c * and as you can see

00:11:50.808 --> 00:11:54.320
the other rows also calculated, updated as well.

00:11:54.420 --> 00:11:54.924
Beautiful!

00:11:55.024 --> 00:11:58.507
So as I mentioned, feel free to look / browse the

00:11:58.607 --> 00:12:00.107
documentation for more flags

00:12:00.108 --> 00:12:02.640
because each flag has its own special meaning

00:12:02.641 --> 00:12:07.139
and will do different things, which is pretty cool.

00:12:07.140 --> 00:12:08.124
All right, cool.

00:12:08.224 --> 00:12:10.007
We're done with debugging and we fixed it.

00:12:10.107 --> 00:12:12.075
So there, now we know how to create formulas

00:12:12.076 --> 00:12:14.207
and how to debug them whenever they break,

00:12:14.307 --> 00:12:15.040
which is awesome.

00:12:15.140 --> 00:12:18.324
All right, but remember how I said that you can

00:12:18.424 --> 00:12:23.659
only debug... Whenever you run recalculate,

00:12:23.660 --> 00:12:25.340
It will only run the first formula?

00:12:25.440 --> 00:12:28.439
Well, let's say you want to have multiple formulas?

00:12:28.539 --> 00:12:30.807
This is completely valid, except the bad thing is

00:12:30.907 --> 00:12:34.090
that you have to do C-c C-c C-c on each each one,

00:12:34.190 --> 00:12:39.457
because C-u C-c * won't recalculate everything.

00:12:39.557 --> 00:12:40.350
It won't.

00:12:40.450 --> 00:12:41.557
Sadly, it doesn't do it.

00:12:41.657 --> 00:12:44.189
There is a way that you can do it,

00:12:44.289 --> 00:12:46.459
which is hacking together some elisp.

00:12:46.460 --> 00:12:47.474
You can probably find it

00:12:47.475 --> 00:12:48.707
or you can probably make it yourself

00:12:48.807 --> 00:12:51.107
if you look around, but that's out of scope for this.

00:12:51.207 --> 00:12:57.099
So now, how do we... We can write all the formulas

00:12:57.100 --> 00:12:59.007
we want in one single line.

00:12:59.107 --> 00:13:01.740
There's a way to to distinguish

00:13:01.741 --> 00:13:03.340
when one ends and one begins

00:13:03.341 --> 00:13:04.707
and that is the double colon (::).

00:13:04.807 --> 00:13:07.607
So right there, and a new formula will begin.

00:13:07.707 --> 00:13:08.374
So for example,

00:13:08.474 --> 00:13:12.224
let's say for the seventh column we say "gopar".

00:13:12.324 --> 00:13:17.407
If I do C-c C-c, it'll run every single thing

00:13:17.507 --> 00:13:19.226
so that... "gopar". Tada!

00:13:19.326 --> 00:13:20.624
There, awesome.

00:13:20.724 --> 00:13:22.440
But this is going to get very annoying if you're

00:13:22.540 --> 00:13:25.007
simply trying to edit formulas like this, right?

00:13:25.107 --> 00:13:26.933
So that's where the nicer debugging,

00:13:27.033 --> 00:13:28.790
nicer editing section comes in.

00:13:28.890 --> 00:13:32.299
So, yes, just like as mentioned, table calls

00:13:32.300 --> 00:13:33.507
only the first formula.

00:13:33.607 --> 00:13:36.349
So what's the step onto this nicer editing section?

00:13:36.449 --> 00:13:40.424
Try out "C-c ," or `org-edit-special`.

00:13:40.524 --> 00:13:44.557
So let's go back to the table formula and call it...

00:13:44.657 --> 00:13:47.590
oh my god, look at that,

00:13:47.690 --> 00:13:49.890
a new buffer just for editing,

00:13:49.990 --> 00:13:52.599
and each formula is in its own line to make

00:13:52.699 --> 00:13:54.624
it easier, which is beautiful!

00:13:54.724 --> 00:13:58.715
So, let's just say I want to do another calculation.

00:13:58.815 --> 00:14:02.607
Let's do eight times eight, which should be 64,

00:14:02.707 --> 00:14:04.740
and we have no need of putting this flag

00:14:04.741 --> 00:14:07.440
because the flag only affects it on the input coming in.

00:14:07.540 --> 00:14:09.074
I should have mentioned that earlier.

00:14:09.174 --> 00:14:10.774
Only input coming in.

00:14:10.874 --> 00:14:13.174
There is ways to affect the output,

00:14:13.274 --> 00:14:16.474
which we'll also cover in this topic later on,

00:14:16.574 --> 00:14:19.131
but for now, you can either leave the end flag

00:14:19.231 --> 00:14:21.990
or leave it out. It will still work fine.

00:14:21.991 --> 00:14:23.507
Let's just leave it out for now.

00:14:23.508 --> 00:14:26.624
Let's just do C-c C-c to make sure

00:14:26.625 --> 00:14:30.690
that everything is working. 64. Beautiful.

00:14:30.790 --> 00:14:33.066
So there you have it. You can have multiple formulas

00:14:33.166 --> 00:14:34.778
just stacked up into one line,

00:14:34.878 --> 00:14:36.390
and whenever you need to edit it,

00:14:36.391 --> 00:14:38.257
just go into that into that line

00:14:38.357 --> 00:14:41.024
and "C-c ,", and tada!

00:14:41.124 --> 00:14:44.350
You have this ready, good to go, and for editing.

00:14:44.450 --> 00:14:45.824
Oh and if you want to exit out,

00:14:45.825 --> 00:14:48.940
also just do "C-c ," again and you're back.

00:14:49.040 --> 00:14:51.890
I did not mention that. Sweet!

00:14:51.990 --> 00:14:54.774
So now we know how to have

00:14:54.775 --> 00:14:57.006
a better editing experience. Sweet!

00:14:57.106 --> 00:15:00.240
So now comes the formatting section which I talked about.

00:15:00.340 --> 00:15:01.874
So what's the first step?

00:15:01.974 --> 00:15:05.507
Well for formatting, Org mode uses

00:15:05.508 --> 00:15:08.574
the printf function from C.

00:15:08.674 --> 00:15:10.374
So those who are familiar with C,

00:15:10.375 --> 00:15:12.823
you'll feel right at home because the way you format it

00:15:12.923 --> 00:15:13.940
is exactly the same way.

00:15:14.040 --> 00:15:16.557
So for example, this will print off

00:15:16.558 --> 00:15:18.873
a floating number with two decimal points.

00:15:18.973 --> 00:15:21.540
As you can see here, this is how you will use it.

00:15:21.640 --> 00:15:26.324
It will be after the semicolon and it will be "%.2f".

00:15:26.424 --> 00:15:28.157
So let's go ahead and test that out.

00:15:28.158 --> 00:15:30.590
Actually, let's go ahead to our latest function--

00:15:30.690 --> 00:15:32.340
I mean, to our latest formula.

00:15:32.440 --> 00:15:33.840
Let's go ahead to the nicer buffer

00:15:33.841 --> 00:15:39.207
and let's do, Ctrl... Let's enter the semicolon,

00:15:39.208 --> 00:15:45.324
and then let's put the percent sign, we do 2f.

00:15:45.424 --> 00:15:49.174
Actually, let's make it five

00:15:49.175 --> 00:15:52.590
just to differentiate from the formula, and let's see.

00:15:52.690 --> 00:15:57.174
Let's run it, and tada!

00:15:57.274 --> 00:16:00.179
So yeah, as you can see, five decimal points.

00:16:00.180 --> 00:16:01.857
and if we want zero decimal points, we can also

00:16:01.957 --> 00:16:04.957
just move point zero, and tada!

00:16:05.057 --> 00:16:06.124
Just like that.

00:16:06.224 --> 00:16:08.774
We can also just leave it as is how it was before,

00:16:08.874 --> 00:16:10.874
because before, we didn't even actually need it,

00:16:10.875 --> 00:16:13.014
but yeah, just an example.

00:16:13.114 --> 00:16:15.090
And just a reminder, there are

00:16:15.091 --> 00:16:17.357
plenty more ways of formatting,

00:16:17.358 --> 00:16:19.640
just look at the documentation.

00:16:19.740 --> 00:16:21.724
There will be more. Basically every single thing

00:16:21.725 --> 00:16:25.574
that you need, just use the documentation as reference.

00:16:25.674 --> 00:16:28.340
Cool! So now we know how to debug,

00:16:28.341 --> 00:16:29.774
how to write formulas

00:16:29.775 --> 00:16:32.824
and how to get a better, nicer editing buffer

00:16:32.825 --> 00:16:35.124
for the formula so we don't have to do it all

00:16:35.125 --> 00:16:36.240
in a single line.

00:16:36.340 --> 00:16:38.657
So, what about conditional prompts, like I was

00:16:38.757 --> 00:16:43.390
showing in the first table in the end goal?

00:16:43.490 --> 00:16:47.299
Well that's actually pretty simple because we already

00:16:47.300 --> 00:16:48.324
know how to do this.

00:16:48.424 --> 00:16:51.133
Yes, if you think about it for a second, if we are

00:16:51.233 --> 00:16:54.221
able to pull lisp s-expressions, then we are able to

00:16:54.321 --> 00:16:56.290
basically do it already. Here's an example.

00:16:56.390 --> 00:17:01.807
We're saying if the second column is empty, is zero--

00:17:01.907 --> 00:17:04.619
so actually, this should be with the N flag

00:17:04.620 --> 00:17:06.940
because we will transform empty values as zero,

00:17:07.040 --> 00:17:08.819
and that's how Org mode will read those.

00:17:08.820 --> 00:17:12.424
It's saying if the second flag is zero,

00:17:12.425 --> 00:17:16.952
then I want you to put "Enter the values."

00:17:17.052 --> 00:17:20.440
And if it's not empty, we're going to put

00:17:20.540 --> 00:17:22.190
"Values entered." We're going to recognize.

00:17:22.290 --> 00:17:24.240
So let's go ahead and actually do this.

00:17:24.540 --> 00:17:28.990
So let's grab this, and let's type it in.

00:17:29.090 --> 00:17:36.457
So let's go ahead. "Enter the values," because it

00:17:36.557 --> 00:17:37.390
doesn't have any.

00:17:37.490 --> 00:17:42.440
So let's go ahead and say "Hello EmacsConf"

00:17:42.441 --> 00:17:47.224
and let's go ahead and run it again.

00:17:47.324 --> 00:17:48.457
Since there are values,

00:17:48.458 --> 00:17:51.574
it's going to overwrite what's here and put value entered.

00:17:51.674 --> 00:17:53.398
So let's go ahead.

00:17:53.498 --> 00:17:55.690
Tada, so there you go.

00:17:55.790 --> 00:18:00.524
So that is pretty much how you do conditional props,

00:18:00.624 --> 00:18:01.940
which is pretty straightforward

00:18:01.941 --> 00:18:02.724
once you think about it

00:18:02.725 --> 00:18:05.440
because if you are able to insert Lisp expressions,

00:18:05.441 --> 00:18:08.240
then you are able to just do that check

00:18:08.241 --> 00:18:11.074
and do the conditional check yourself.

00:18:11.174 --> 00:18:13.540
So, custom formulas.

00:18:13.640 --> 00:18:15.324
Yeah, you'll see what I mean.

00:18:15.424 --> 00:18:19.924
We want to be able to put our own custom functions,

00:18:20.024 --> 00:18:23.890
and you probably have an idea how to do this already.

00:18:23.990 --> 00:18:27.059
Yes, we also know how to do this already.

00:18:27.060 --> 00:18:30.357
Before I continue, I'm going to say that I already

00:18:30.457 --> 00:18:31.940
have some formulas that I use

00:18:31.941 --> 00:18:33.374
which are not part of this talk

00:18:33.375 --> 00:18:37.390
because they're just functions that calculate some stuff.

00:18:37.490 --> 00:18:39.990
So for example, they calculate the monthly mortgage,

00:18:40.090 --> 00:18:43.257
the monthly PMI, property tax, homeowners insurance,

00:18:43.357 --> 00:18:44.757
so a bunch of other stuff.

00:18:44.857 --> 00:18:49.729
I have these functions already and they are a bit off,

00:18:49.829 --> 00:18:52.212
but for this example, they're doing everything.

00:18:52.312 --> 00:18:54.390
It's close enough, so don't worry too much.

00:18:54.490 --> 00:18:56.824
Just an example, you can have your own function

00:18:56.924 --> 00:18:59.213
that does something else like calculate

00:18:59.313 --> 00:19:01.540
a REI B rental or something like that.

00:19:01.640 --> 00:19:03.219
So you can do whatever you want.

00:19:03.220 --> 00:19:04.724
As long as you can call via Lisp,

00:19:04.824 --> 00:19:07.899
you can call it in Org mode, in the table formulas.

00:19:07.900 --> 00:19:11.337
So let's exit out of there.

00:19:11.437 --> 00:19:13.807
Now that we know how to do everything,

00:19:13.808 --> 00:19:20.924
let me go back to the original table and go from there.

00:19:21.024 --> 00:19:26.524
Let me close all these out actually.

00:19:26.624 --> 00:19:29.524
Now let's go back and revisit this table,

00:19:29.624 --> 00:19:31.619
since we'll be much, much more familiar

00:19:31.620 --> 00:19:35.418
except for one thing, which I will explain.

00:19:35.518 --> 00:19:38.040
So we have the constants right there

00:19:38.041 --> 00:19:39.690
and we have the house prices

00:19:39.691 --> 00:19:42.499
and we have everything just like I mentioned before.

00:19:42.500 --> 00:19:44.023
The main part that we want to look at

00:19:44.123 --> 00:19:45.024
is the table formula.

00:19:45.124 --> 00:19:47.474
So let's open up our special editing buffer,

00:19:47.574 --> 00:19:49.674
"C-c ,",

00:19:49.774 --> 00:19:52.390
and as you can see, I have some right here.

00:19:52.490 --> 00:19:53.524
So, the fifth column I'm saying,

00:19:53.624 --> 00:19:55.824
"Hey, we're gonna call this function

00:19:55.924 --> 00:19:58.557
rei-calculate-down-payment, and I'm gonna

00:19:58.657 --> 00:20:00.757
pass in the third column and fourth column

00:20:00.758 --> 00:20:02.339
and I'm going to pass in t." (true)

00:20:02.340 --> 00:20:05.874
I believe this is just to normalize,

00:20:07.174 --> 00:20:12.057
to convert to the proper decimal place,

00:20:12.157 --> 00:20:14.079
so let's not worry too much about that.

00:20:14.179 --> 00:20:16.690
Then for the sixth column, we're going to say

00:20:16.790 --> 00:20:18.045
"I calculate the monthly mortgage."

00:20:18.145 --> 00:20:20.124
We're going to pass in the third column

00:20:20.224 --> 00:20:21.339
the INTEREST_RATE, which we have

00:20:21.439 --> 00:20:22.979
defined over here in the constants.

00:20:22.980 --> 00:20:26.274
The 30, I believe this is for 30 years,

00:20:26.374 --> 00:20:29.323
PMI, the PROPERTY_TAX and HOME_INSURANCE,

00:20:29.423 --> 00:20:30.774
and then the fourth column.

00:20:30.874 --> 00:20:33.824
Then everything is going to be accepted as numbers,

00:20:33.924 --> 00:20:35.074
and we're going to have two decimals

00:20:35.174 --> 00:20:36.174
at the end of the place.

00:20:36.274 --> 00:20:37.507
So, what else?

00:20:37.607 --> 00:20:40.074
Over here is where we have our conditionals.

00:20:40.174 --> 00:20:42.274
We're saying, "hey, if the seventh column is 0,

00:20:42.374 --> 00:20:44.302
press 'Enter Tenant Income'."

00:20:44.402 --> 00:20:48.407
Over here as well, if the seventh column is zero,

00:20:48.507 --> 00:20:51.724
we're going to press 'Enter Tenant Income'

00:20:51.824 --> 00:20:53.605
and for this one we're going to say,

00:20:53.705 --> 00:20:55.940
"Hey, we're going to normalize the price."

00:20:56.040 --> 00:20:59.240
I believe this is a 1% rule.

00:20:59.340 --> 00:21:01.390
This could have been extracted into a function,

00:21:01.490 --> 00:21:03.939
but I just did the calculation right here.

00:21:04.239 --> 00:21:07.890
This, I believe, is the ROI, 12 months.

00:21:07.990 --> 00:21:11.007
This is just calculating the cash flow.

00:21:11.107 --> 00:21:14.907
This is a very rudimentary function or formula.

00:21:15.407 --> 00:21:16.732
Do not use this because there is way more

00:21:16.733 --> 00:21:18.840
to go into calculating the cash flow

00:21:18.841 --> 00:21:21.499
and also, it differs from person to person.

00:21:21.599 --> 00:21:23.774
Some people are more conservative,

00:21:23.874 --> 00:21:26.959
other people are way more liberal, so it just

00:21:26.960 --> 00:21:28.874
depends how you want to calculate it.

00:21:28.974 --> 00:21:34.240
As you can see, we have the N flag for numeric number

00:21:34.241 --> 00:21:36.090
and then we're saying we're formatting

00:21:36.190 --> 00:21:37.694
to one decimal place.

00:21:37.794 --> 00:21:43.207
The %% sign is just to input a percent sign as itself.

00:21:43.208 --> 00:21:45.419
Otherwise, Org mode is going to think

00:21:45.420 --> 00:21:47.940
it's some type of a formatter, which it's not.

00:21:48.040 --> 00:21:49.140
If you do... As I mentioned,

00:21:49.240 --> 00:21:51.690
if you've used the printf function in C or C++,

00:21:51.790 --> 00:21:55.507
then you probably know how to use it.

00:21:55.607 --> 00:22:01.824
Okay, so this is pretty much everything in a nutshell.

00:22:01.924 --> 00:22:04.970
So, one thing that I do want to say

00:22:05.070 --> 00:22:06.379
is the last section,

00:22:06.479 --> 00:22:07.774
which is automatically updating,

00:22:07.874 --> 00:22:10.174
which is the part that blew my mind

00:22:10.175 --> 00:22:11.457
when I realized that Org Mode can do this.

00:22:11.557 --> 00:22:12.477
So how do we do it?

00:22:12.577 --> 00:22:14.659
Well, you probably guessed just from looking at

00:22:14.660 --> 00:22:18.324
at the first table that we have right now.

00:22:18.424 --> 00:22:20.774
We add a column at the beginning

00:22:20.874 --> 00:22:22.857
of the table with a percent (%)--

00:22:22.957 --> 00:22:24.857
I'm sorry, with the pound sign (#)

00:22:24.957 --> 00:22:28.457
or hashtag as the younger kids call it.

00:22:28.557 --> 00:22:31.045
So this is what we do.

00:22:31.145 --> 00:22:32.819
We added a column at the beginning of the

00:22:32.820 --> 00:22:34.984
table, we do pound sign (#).

00:22:35.084 --> 00:22:35.790
So this is what it's for.

00:22:35.890 --> 00:22:38.839
This lets Org mode know that "hey,

00:22:38.840 --> 00:22:41.140
I want the values, the table formulas,

00:22:41.240 --> 00:22:43.957
to automatically run on each tab change."

00:22:44.057 --> 00:22:46.240
Now I believe that you can make it so that

00:22:46.340 --> 00:22:49.123
it changes, so that it updates on every keystroke.

00:22:49.223 --> 00:22:51.024
I think that's too much.

00:22:51.124 --> 00:22:53.007
And then you can also make it so that

00:22:53.107 --> 00:22:56.019
only certain rows update or certain columns.

00:22:56.020 --> 00:22:58.219
There's a plethora of things that you can do.

00:22:58.319 --> 00:23:00.924
You should definitely read up on the documentation,

00:23:01.024 --> 00:23:03.425
because you will probably make a way better talk,

00:23:03.525 --> 00:23:06.974
a way more advanced talk than I on this one,

00:23:07.074 --> 00:23:09.574
so I'm looking forward for that.

00:23:09.674 --> 00:23:12.459
But this is essentially how you build

00:23:12.460 --> 00:23:15.507
a Org mode table formula that will help you know

00:23:15.508 --> 00:23:17.125
if a property is correct.

00:23:17.225 --> 00:23:22.340
So, let's go ahead and as a final out to this demo,

00:23:22.440 --> 00:23:25.419
let's go ahead and enter a new column.

00:23:25.420 --> 00:23:30.174
Org-mode automatically puts the pound sign (#),

00:23:30.274 --> 00:23:35.440
which is awesome, and let's just say 'Emacs House',

00:23:35.540 --> 00:23:39.590
and let's say it is 100k.

00:23:39.690 --> 00:23:44.339
So 100k, and as you can see it's already trying to

00:23:44.340 --> 00:23:46.040
calculate the monthly mortgage,

00:23:46.140 --> 00:23:47.090
but we'll see about that,

00:23:47.190 --> 00:23:49.879
and let's just put 10% down.

00:23:49.880 --> 00:23:53.057
So 10% of 100k should be 10,000.

00:23:53.157 --> 00:23:56.407
So 10,000, correct, and the monthly mortgage is that

00:23:56.408 --> 00:24:00.090
and let's just say the tenant income is,

00:24:00.190 --> 00:24:01.657
as you can see right here,

00:24:01.757 --> 00:24:05.874
tenant income is, let's say 1500.

00:24:05.974 --> 00:24:07.274
Is it passing the 1% rule?

00:24:07.374 --> 00:24:09.424
Yep! What's my ROI?

00:24:09.524 --> 00:24:13.879
118%, which is kind of cool actually.

00:24:13.880 --> 00:24:14.707
That's a nice deal.

00:24:14.907 --> 00:24:17.657
So this is a rudimentary way of

00:24:17.757 --> 00:24:20.319
calculating deals in Org mode.

00:24:20.419 --> 00:24:44.380
I hope you found it interesting, and yeah, that is it.