Creating a legend
Video: Creating a legendMap legends let the reader know what symbology choices you've made, and help them to send the message or story that you're trying to tell. Legends include examples of the various point and bind styles that you've chosen for your map features, and describe how features may have been classified in the groups, either by graduated symbol sizes or by using a customized color ramp and sequential color patches like we have here with our populations. Though the Table of Contents includes all this information for your own benefit, when outputting the map it usually needs to be noted somewhere on the map sheet itself. Now that we have two data frames here though, we have to pay attention to which one is currently the active data frame.
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Get up and running with ArcGIS, a true geographic information system (GIS) that allows you to dig into highly accurate geospatial data in a way other mapping applications can't compete with. It's great creating maps, analyzing data for land use studies and other reports, and preparing data for use in an application or database. Let Adam Wilbert show you how to display, analyze, and illustrate geospatial data with ArcGIS. He explores how to import data from multiple sources, manage it with the ArcGIS catalog, and then start making maps. Learn how to lay out your data in the ArcMap component; add symbols, scale bars, and legends; and get your maps out of ArcGIS and into the real world, whether it's for printing or export to another application.
- Understanding vector vs. raster data
- Modifying metadata
- Adding data to a map
- Importing data from online providers
- Labeling features
- Joining data
- Clipping data to a study area
- Working with map layouts
- Creating a legend
- Printing and exporting the map to a file
Creating a legend
Map legends let the reader know what symbology choices you've made, and help them to send the message or story that you're trying to tell. Legends include examples of the various point and bind styles that you've chosen for your map features, and describe how features may have been classified in the groups, either by graduated symbol sizes or by using a customized color ramp and sequential color patches like we have here with our populations. Though the Table of Contents includes all this information for your own benefit, when outputting the map it usually needs to be noted somewhere on the map sheet itself. Now that we have two data frames here though, we have to pay attention to which one is currently the active data frame.
I can see which data frame is the active data frame by looking for the bold text over here in the Table of Contents. This one here, this new data frame, is our locator map that we added in the last movie. And it's currently the active data frame. I can also see a faint dotted line around this map here, indicating that this is also the current data frame. What I want to do is create a legend, but not for the data frame down here. I want to create a legend for the main map up here. I can make this the active data frame, simply by clicking on it. And you'll see that the dashed border goes up here. Or in the Table of Contents, I can right click on the data frame's name here, and choose Activate from the menu.
Now that this is the active data frame, I can go up to the Insert menu here and choose Legend. That will open up the Legend Wizard, and it will ask me which elements from my data frame I want to appear on the legend. Over here is a list of all of the elements or layers that are in that data frame. And over here are a list of all the items that'll appear on the legend. Now I want to visualize in the Legend the point symbol that I have for dairy farms. And I also want to symbolize the population symbols that we have here. But I don't necessarily need to symbolize the Washington state colors. I think it's going to be pretty obvious that blue means water, and gray is not Washington.
So I could take this legend item here and move it back off of the list. Okay, go ahead and say Next. The next screen asks us what kind of title we want for our Legend. We can give it a different name if we like. We can also change this font color in properties here. I'm going to go ahead and leave the name Legend. I think that's fine. Go ahead and say Next. We can also apply a Border or Background color. And these are just drop down menus with various styles that we can choose from. For instance we can add a one point line, we can add a background of a light cyan color. We can also add a drop shadow of a gray 30%.
I'll show you what that looks like, go ahead and say Next. Here we get to stay how large our patches are going to be in the legend. We can make choices here or we can see the legend in the place, and make the changes after the fact. I'm going to go ahead and accept the defaults here, and we can go back and change them if we want to later. Go ahead and say Next. Again, spacing and everything can be changed later, so let's see how the default Legend looks first, and then we might go back and tweak a little bit. Go ahead and press Finish, and we'll create a Legend. Now we have a Legend on the screen here. We can drag and drop it around, just like every data frame.
So I'm going to move it over here on the right. If I want to go back in and further change the style of the Legend, all I need to do is double click on it. It will bring me right back into the Legend Properties. Here on the General tab, we can change the Name, and what items appear. On the Items tab, we can individually style the way the text appears for each different item. On the Layout tab, we can adjust the spacing and everything. So I can click in here and change the spacing and it'll tell me which elements are going to be spaced out, by changing these point sizes here. In the frame section, we can adjust the Border, Background, and Drop Shadow. And I find this to be a really busy legend, so I'm going to go back and change this back to the blank style.
We'll scroll up and say no Border. I'll say no Background and I'll say no Drop Shadow. And here we could accurately position our Legend on the page. Now we've already see how we can use these guidelines over here on the map layout in order to lock things into position. So we don't necessarily need to use this particular tab. Okay I'll go ahead and press Apply to save those changes to my Legend. And you'll see the Legend over here updates. Go ahead and say Okay. Now the nice things about the legends here on ArcMap is they're tied over here to the Table of Contents. So If I make a change in the Table of Contents, the Legend will automatically update over here. For instance, let's clean up this titles a little bit.
They're a little bit cryptic. Here we're going to select the Dairy Farms. I'm going to click on it once. And then pause and click on it again to make it editable. And if you accidentally double-click on it that will just open up the Properties, and you can just switch over to the General tab and just edit the name as well. I'm going to call this Dairy Farms. And go ahead and say Okay. The next one down is our counties, here. So I'm going to click on it. And then click again, and I'll call it Counties. Now this line here that says pop ten divided by a land my is how we decided to symbolize our counties. Basically what we're looking at is people per square mile, and that's an easier way to say that. So I'm going to click on this and change that as well.
And I'll call it People Per Square Mile. And you notice that updates in the Legend over here as well. So that's looking pretty good. So one last thing we can do to edit our Legend, if we right-click on the Legend and select Convert to Graphics, it'll no longer be linked to our Table of Contents. But we gain the advantage of being able to move elements of the legend wherever we want on the page. So I've converted to Graphics, and one more time, I'll right-click on the graphic and say Ungroup. And that'll ungroup all the elements so that they're individualized. And I can drag and put these pieces wherever I want on the map, so maybe I want the dot for dairy farms to appear down here, and maybe I want the title Legend to appear over here.
And maybe I can move these guys, and I'll shift click to select a bunch of them. And I'll move those down here. And, I can click these three here and shift+click to select all of these and move them next to it. So, you can see, you can arrange this in any position that you want. So, not all maps require a legend, though. Some maps use very standardized symbology or are self documenting in a way that a legend is just redundant information. However, when a color ramp or graduated symbol classes are involved, it's usually the case that a legend will help clarify the map's message and help your readers understand what your map is all about. While the basic process is very automated, by digging into the properties for each element, or by converting it to a graphic you can dial in the legend to look exactly how you would like.
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