Hey again, in this video we're going to talk about the jittered map I showed you on my dashboard. I've included some written instructions about how to make the map with the course materials. So, we're not going to go over every single detail here, but I did want to show you a couple of things that I think would be useful for you to see visually. And I did want to point out, one place in particular that, I think if you're going to get tripped up, that's where you'll get tripped up. So, let's go ahead and take a look at how you make this thing. So this is my version of the jittered map. And let me just talk you through what it's doing in general again. So the reason we're using this jittered map is that it would be useful to be able to see all the properties within a given location that are profitable. And also, to see for each property, whether it's a one or two bedroom house or apartment. In order to do that, you have to be able to separate the points, and there is no good way, built into Tableau, to do that. If you try to make a map like that, you would either end up with something like this, where you have a different size depending on how much profit you have or how many profitable properties you have. Or, you would end up with something like this where you just have one single data point, and you'd have to hover over it, say, to find out how many profitable properties were in each location. So that's not very informative, that doesn't tell you exactly what you want by eye. So the jittering technique says, take all the data that you're interested in, look at it and say okay, if there are any data points that are in the same geographic location, put them in a cluster. Then, we're going to distribute that cluster into a circle. The center of that circle is going to be on that shared common location. What the instructions allow you to do and show you how to do is change how wide the circle is relative to the center point, the center shared location, and change how the circle turns around. So I just wanted to show you what that looks like. And again, this is all going to be in the instructions, this is just to show you what it looks like. So there are two parameters the instructions tell you to make. One is spread_factor and spread_rotation. Let's go ahead and open those and take a look at them. And this is a good reminder about how to bring up a parameter control in your worksheet. So I'm clicking on the drop-down and I'm bringing up Show Parameter Control. So the spread_factor is going to, it basically defines the radius of the circle. And I should also say that all the calculations you'll see are based on just the geometry or the equations of how to make a circle. So let me zoom in, actually make this a little bit clearer, let's go down to Texas, Texas is a good state, it has a lot of properties in this part of the visualization. So, each one of these is a mark. You can change the colors, of course, or the size. Let's make the size a little bit bigger since we've zoomed in. So, what the spread factor will do is it will change how wide the circle is. So, right now it's one. If I change it to two, the circle is going to get wider. If I change it to 0.5, the circle is going to get smaller than it was before. And the smaller it gets, the more the points are going to overlap so you will want to change the size accordingly. Let's make it back to 1 again. The spread rotation, it basically turns the circle around. So it's interesting, I don't find it that useful. But watch what happens to, say, this green dot if I change the spread rotation from 40 to 80. You can see, it just turned around and you can do that in a bunch of different ways. So that's what the basic parameters do. Now the part that I want you, there are two things actually where you might get tripped up. Let's make this look a little prettier again. The first thing you need to know is that if you look at my visualization here, you'll see that I have a longitude and a latitude value up here. Now the thing is that we have to make a calculated field that uses that longitude and latitude, because we have to adjust the longitude and latitude from its original point to go to the circle. The annoying thing is that Tableau doesn't allow you to use its automatically generated latitude and longitude values here, which is what it uses to make the map in calculated fields. So, you have to do this workaround. What you have to do is you have to make a map like this, where you display all the geographic locations you're interested in. Then you're going to have to export this data, and again, all these instructions are written down, but you can right-click View the Data. And what's going to happen is, now these are real values. So when you export the data, you're going to be able to use these values, which are the same as those that are automatically generated. But you're going to actually be able to use them because they're not going to be traded in the same way as these automatically generated ones. So you'll export them and then you are going to blend the data back in to your current work space, your current work source. So that you can use the latitude and the longitude values in calculated fields, which is what you have here, so make sure you pay attention to that step in the instructions. The other place where you might get tripped up, let's go over here, is that you have a lot of calculations in this visualization. And what I said before when I was describing what the general approach of the visualization is should give you a hint about where you might get tripped up. Because I said that it looks at, okay, within everything that's displayed here, put all of the data points that are in the same geographic location in one group. What that means is, it's only looking at the stuff that's in the work space. That means it's going to use table calculations. Remember, row calculations make a different calculation for every single row in the data source. Table calculations do different types of calculations based upon what's in your workspace and what you're actually seeing right now. Now that you've taken the SQL course, I can tell you that table calculations basically act like subqueries or multiple subqueries. They let you make derived tables and work with derived tables and they let you make nested subqueries. That's why they're dependent on what you're actually seeing in your visualization at the time. So you're going to have a lot of table calculations that go into this visualization. And remember, every time you make a table calculation, you have to tell Tableau how to compute it, and what to do with the other variables that are in your workspace. You can think of this again, like SQL, you have to be able to tell the database what to do with those other variables every time you're going to aggregate it in a different way. So the reason why that can be tricky, so I'm going to go up to these as examples. Remember you can go, when you have to, when you're going to tell Tableau how to make the table calculation you do the drop-down, you click in the drop-down, and you click on Edit Table Calculation. The trick is that you have to remember to tell it what to do, using again, I told you, I always suggest you use the advanced option. But you're going to have to do it for every calculated field within that calculated field. So there are actually three different calculated fields In this one pill, and you have to make sure that you check the correct partitioning and addressing options for every single one of them. So if you get confused, or if you have a hard time and things aren't working, mostly likely it's because you forgot to tell Tableau what to do with every single field that's in each one of these table calculations. The one other thing I should mention about table calculations, is if every time you add another measure or dimension to your workspace, you will likely have to redo all of your table calculations. because again, you'll have to tell Tableau every single time what it should do with that new variable you just put in. Think of it again in SQL terms and it will help you remember why that's important. The one last thing, I'll take this opportunity to show you is you've been seeing in these visualizations that every time you hover over a data point usually there is some useful information there. Tableau does automatically put stuff in that tool tip. But you can edit what is in that tool tip and you can actually do very pretty things in the tool tip if you have the energy and want to. The way you edit that is you go to the tool tip button, click on the tool tip button and anything that doesn't have these symbols around it and that aren't in gray will be written verbatim. But you can insert variables, each one of these are variables. You can insert them so that they're dynamic and represent things specific to the data point by going to Insert and then it will give you all the options. It'll let you put in anything in your workspace or any of your parameters. You can change the formatting in all of these so you can make parts of it green if you wanted to, by changing the color here or changing the font or the size. So hopefully that helps give you an idea of how the jittering technique works. I know that this map will probably take you a little bit longer than some of the other visualizations you'll be making in this dashboard, but the time will be worth it. First of all, it really helps you understand many aspects of how Tableau works, including blending and it reminds you about table calculations. But it's also a really great tool to have in your back pocket for the future. It's also a great visualization to be able to show potential employers so that you can show how good you are at Tableau and all the tricks you know how to do. So good luck with it, and I hope you have fun.
