[MUSIC] Hello, everyone and welcome back. In this lecture, I'm going to show you a few tools not super in-depth but I want to make sure that you know exist. In fact, we'll do this for the rest of this module, I'm going to show you just a handful of tools that you should know about that you can potentially apply them when situations come up but that we'll just do a quick overview of now. Each of them is pretty simple and more of a utility tool than straightforward analysis tool. They're the kinds of things that you put into a chain of other processing. So, in this video I'm going to show you a few tools related to raster analysis, the kinds of things that you will probably put into raster calculator but then you can also run on their own. And to start with, let's make a Euclidean Distance raster from these points here just to have a particular raster to work with.. So, we go to distance and spatial analyst and I'll look at the Euclidean Distance and select the Observer Locations, and I don't really care where it's putting it. I'm going to say Maximum distance is 5,000. And we'll make the Output cell size, 5. And, I'll say "OK". Okay, and let's just symbolize this with a standard gray scale. So that we just kind of see the basic distance away and let's also make it continuous. So classified, we'll make it stretched and click OK. Okay, and a few things I want to show you are the conditional tool set and then the math tool set, and we'll explore the conditional tool set in the next video just a little more. We'll look at Con and Set Null which are tools that evaluate conditions are if statements, if you've heard of that before. So, since we will look at those in the next video, let's move on a bit. But then, let's also look at the Math tool set here. And some of you are probably seeing logarithms here and exponents, in division, and thinking. Let's go do something else. [LAUGH] Let's go look at another tool set, or something. But, this doesn't have to be, particularly, scary, and what I really want you to know is, that these tools and these tools and in fact, all of the tools in Spatial Analyst are available in the map algebra window. And I can call any of them as long as I know what name they go by in this raster calculator. And in fact, you can see the conditional toolset and the mountain toolset In the trigonometric tool set here. All up here, directly in this box here for convenience to put into your expressions in your raster calculator. So that's one take away, is that's all available right here. But then, a great way to learn about what these things are and how to use them is to actually just run message geoprocessing tool. So one, I want to point out right now is the mode tool or the modulo tool. Now, in math, modulo give us a remainder, so it finds the remainder of the first raster when divided by the second raster on a cell-by-cell basis. So, let's think about that for a second. We can also use a constant value instead of another raster, so if we take our Euclidean distance and put in a constant value of 100. What do you think we're going to get back if it gives us the remainder? Well, it's going to divide the distance raster by a 100 and give us whatever the remainder value is from the division. And just in case you don't remember what remainders are, because we've dealt with fractions for most of our lives. Remainder instead of giving you a fraction, remainder is the value that's left over that you divide the number, whatever it is. In this case a 100 into the number that you're dividing as many times as it'll go, and then at some point you don't have enough to divide it again, and so you have a remainder. So, if we had 531 and we are dividing by 100, the remainder would be 31 and that's what modulo gives us. It discards the number of times it divides and gives us just the remainder. The example I'm going to show you of using it is a little trivial, but there are legitimate use cases. A lot of times modulos are used to find all of the even numbers or something. So, in this case you would do module 2 and then let's go take a look at the output so that that actually makes sense. Let's run it by 100 in this case. And we'll do mod.distance 100. So, kind of psychedelic looking, we'll zoom in a bit and see what we actually have. So, we have these rings around it now and if we look at the color ramp we have 0 to 99. So, it doesn't go to 100 because if it goes to 100 it no longer has a remainder, right, it goes back to 0. So, right at the point, the remainder is 0 because it divides 0 times, and then slowly, the remainder grows all the way up to 99 and then we get to 100 meters away again. So, we have to pick 97 and then just past 100, and it sets back to 0 or 1 around here. Now, the roster's not perfect because we're not always a perfect variant of 100 away. So, what we can do is actually see that in action if we use another roster calculator expression. So, let's take a look at that and if I take my point distance raster or my modular raster and say were equals 0 which is where there's no remainder, so a hundred divided in evenly and run okay. I could see that it's kind of scattered, right. So, in these locations it divided in perfectly. But in the spots in between, it's probably some low number in that part of the ring. So that's part of roster's cell sizes and sampling. Now, in this case, since we had our remainder of 0 is where 100 divides into the distance of these points evenly. And then, we did an expression that when it evaluates to true, equals 1. So the green value of 1 is where we're dividing it evenly and the 0 value is where it has a remainder other than 0 and so didn't divide evenly. What if we just wanted a raster whose cells were only the locations where it divided in evenly where we're exactly a hundred meters or a multiple of a hundred meters away from these points. Well, that's where I can use that set null tool. So, I can put in either raster in this case, but let's just continue on the train we're on with the raster calculation here. And I'll say for my expression, value = = 0. So, all the places where the remainder was something other than 0 are now 0 in this roster calculation and so I want to set those cells to null where this condition is meant, where the roster value is equal to 0 otherwise, it can give me the value of roster calculation. So, where this condition is not true, where the cell value is not equal to 0 It's going to provide B cells back as it is now. So, let's go and click OK. And it looks like it failed and I used an invalid statement. So that's because it's a SQL query, not a roster calculator expression in this case. So, value equals 0 should have 1 equal sign. And it ran correctly, and notice that it has just one value. And if I turn off this other roster, and this other roster, in fact all of them. I can just see only those cells are now available to me. So this is a really trivial workflow, but it shows you the modular tool. And how we can integrate that with our roster calculator workflows to get in subset only to the cells that we particularly want from a roster. A few other tools worth pointing out in here are the logical tools and so you can check if cells are null and do something with those and then the diff tool is kind of interesting. It determines which values are different between the two rosters. And then, if the values are different, it'll keep just the first value. So, it can be a way of having some sort of roster mask that lets you extract values from cells in sort of a reverse way of our typical roster extraction. And a similar tool for this is the n list tool, and what it does is it checks whether the value in the input raster is in any of the rasters that we list. And if it finds that value in any of those rasters, it keeps it and otherwise it sets a null or no data value in the output raster. So again, another way of sort of, extracting data from a raster, after checking it against the number of other rasters. Okay, that's it for now. These tools aren't anything huge, but they're things you should be aware of. I encourage you to also look through the rest of the tools in these toolboxes. Because sometimes you might have some rasters that you need to do some basic math on to transform them. We can use a raster calculator for simple things for unit conversions from meters in a raster to feet or something like that. There are lots of different ways to use just these tools, or use them in the map algebra window here, the raster calculator window. And you can do anything from very simple to very complex statements and workflows using all of these tools chained together. You don't have to memorize them right now but just make sure to keep them in mind whenever you are considering a workflow with rasters. Okay, in the next lecture we're going to take a look at Con and Set Null just a little bit more. Okay, see you there.
