When you are assembling a series of datasets for a new project, you may find that some of those datasets are really large and go far beyond the geographic scope of your study area. So for example, you might be making a map of a neighborhood or even a city, but you've got say, roads for an entire state or province or country. It's a lot of data that you don't need, it takes longer to draw, it takes up too much storage space, whatever the reason might be, because you want a way to be able to cut down that dataset, and just clip out the data that you want to keep for your study area and get rid of the rest. That's where the clip tool comes in handy. The clip tool is often referred to as a cookie cutter for good reason. If you have a dataset like this, this is from the dialogue box help for the clip tool. So, this is the data that we want to do the clip. Two are on, and this is the cookie cutter. So in other words, if you've ever made cookies where you roll out the dough and you have the shape of whatever a snowman or something, and you press that into the dough, and it cuts out the shape of whatever the cookie cutter is, and essentially you're removing the rest of it. That's what's happening here. So it's just a circle here but it can be any shape that you want. But the result is, is that you keep only the data that's inside the cookie cutter's shape. So for example, if I've isolated areas that I know are in low-income neighborhoods, I may want to look at just the libraries that are inside those low-income study areas. So, these are all the libraries for the city of Toronto, and what I'm going to do now is use the clip tool to clip out only the libraries that are inside the purple polygons. So here I'm going to use the clip tool that's inside the extract toolbox, which is inside the analysis toolbox, which is inside arctoolbox. You can really just think of these as folders. It's just a way of organizing the tools together that Ezri has used to manage things. So that's one way to find then you can use the search tool as well. You'll get familiar with finding these tools the more experience you have working with the software. So, we're going to select the clip tool, that brings up this dialogue box, and you can see that I'm going to clip the libraries feature class based on my low-income feature class, so that's going to be the cookie cutter. This is the dataset that I'm going to clip, and it's going to create a new feature class which will be just the libraries inside the low-income areas. So that's the result. It's just kept the data that's inside the cookie cutter, in this case, the purple polygons and removed everything else. One thing to point out, is that it also carries over the attributes for any of the points that are inside the clip boundary, so it is actually preserving all of the original data but only for the areas that are inside the cookie cutter. Just to show you some other scenarios, you can clip points or lines or polygons. In this case, I'm going to clip some polygons. So here, I've got some park boundaries from the city of Toronto and the low-income areas that I've identified, and I'm going to clip out areas that are parks or essentially, I'll think of them as a green space that are inside my low-income areas. So, I've specified parks as the feature class, and I'm going to clip, I'm going to use the low-income as my cookie cutter, it's going to create a new feature class for that. So now, I've got a new feature class as parks inside the low-income areas. So you can see that that's all that's being kept. So, just to make sure this is clear. I hope this is obvious from what I'm showing you. The cookie cutter doesn't have to be just one polygon or one shape, it can be multiple polygons, like I'm doing here. I just want to show you that you can actually get some fairly complex things happening. It doesn't just have to be, I'm going to clip out everything inside the city boundary or something like that, it can be clipping based on anything you want really. By the way, once you've completed this operation, you can right-click on any of the fields in the table and select generates statistics. So, you'll get this little statistics dialog box, it's not being stored anywhere, it's just for you to use interactively. So, you can see, for example, that I've generated statistics for the shape area, and we get a count of how many polygons there are, and some basic statistics there, as well as a histogram which indicates pretty well visually that most of the green space inside those low-income areas are quite small in size and there's very few of them that are large in size. So, this might help us in terms of looking at equity in terms of access to green space or so on. You have to be careful because I've clipped those. I've automatically made those areas smaller than they would have been outside of those areas, but I'm just using this as a scenario to show you that not only can you do clipping, which you can then look at the summary statistics to get a sense of what did I get after I finished my clip.
