Understanding GIS. David Smith
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to the income value.
1)Using the Appearance tab, open the Symbology pane for the block_groups layer.
2)In the Symbology drop-down list, click Graduated Symbols.
3)In the Field drop-down list, click MEDHINC_CY.
4)Click the Classes drop-down arrow and click 3.
5)Replace the first value with 50000 and the middle value with 100000 and press Enter.
6)Click the Template symbol (underneath the Maximum size drop-down box) to open the Format Point Symbol pane.
7)Under Properties, click the Color button and change its color to Tourmaline Green.
8)Click Apply and then the back button at the top of the pane. This symbology sets the color and shape of the symbols that will be used to represent income values.
9)Click Background (to the right of Template) to open the Format Point Symbol pane again.
10)Change Color to No Color, if necessary, and then change the Outline color to No Color.
11)Click Apply and then the back button at the top of the pane.
This symbology makes the block group polygons themselves invisible. All you’ll see are the income dots spread around the map.
12)Change the Minimum size to 8.
13)Change the Maximum size to 24.
14)In the Label column, double-click on the first label (< 50000) to make it editable. Type Low, and press Enter.
15)Replace the second label with Medium. Press Enter.
16)Change the third label to High. Press Enter.
17)Close the Symbology pane.
At the present scale, the symbols overwhelm the map.
Set a visibility range for the block_ groups layer
Earlier, you set a maximum scale value for the World Boundaries and Places layer. Here, you’ll set a minimum value for the block_groups layer.
1)With the block_groups layer selected in the Contents pane, open the Appearance ribbon.
2)Click in the Out Beyond box and type 100000. Press Enter.
The symbols disappear from the map. In the Contents pane, the layer’s dimmed check box indicates that the layer is turned on but is not visible at the current map scale.
3)Zoom to the Dodger Stadium bookmark.
4)Click the Fixed Zoom Out button a couple of times until some of the Medium and High symbols begin to appear.
5)Turn the tracts layer back on.
Now you can start to get a general sense of household income and population density along the river, and look at these variables in relation to park locations.
Search for likely park areas
Clearly, you’re taking an incomplete initial look at a complex problem. You haven’t considered all the requirements (for example, the presence of children). You’re not making any exact measurements of distance. Your data classifications are casual: you don’t yet have a good reason to say what values should count as high population density or low median household income in the context of your project. Nevertheless, you can form some meaningful impressions. You won’t be able to say of an area that a park should definitely go there, but you might be able to identify likely and unlikely areas. Later, it will be interesting to see how well these impressions are borne out by analysis.
1)In the Map Scale box at the bottom of the map pane, highlight the current value. Type 40000, and press Enter.
2)Pan south to where the river crosses the city boundary.
You’ll follow the river to its source, marking good areas for a park along the way. A really good area would have these properties:
•high population density (dark red),
•low median household income (small green dot),
•no existing park nearby, and
•close to the river.
3)Pan slowly north.
Less than a mile north of the city limits, on the east side of the river, are a couple of tracts—one dark red and one medium red—with small green dots. They’re pretty close to the river, and even though there are some parks in the general vicinity, it’s probably worth marking the area as a potential park.
To mark the area, you’ll use a feature of ArcGIS Pro called Map Notes. Map Notes are layer templates that create point, line, and polygon feature classes in your Home database with predefined symbols for feature creation and editing.
4)On the Insert tab, in the Layer Templates group, click the Bright Map Notes button.
Clicking the button adds a new group layer to your Contents pane named Bright Map Notes.
5)Expand the Bright Map Notes layer to see that it contains point, line, and polygon layers.
6)Expand the three layers to see their predefined symbols.
7)Collapse the Bright Map Notes group by clicking the little arrow to the left of the check box.
8)In the Catalog pane, browse and expand your home database in the Databases group. Notice that three new feature classes have been added to the geodatabase. These classes are the data sources for the Map Notes layers that were added to the map.
Create a new feature
You will now create a new feature in the feature class.
1)Go to the Edit ribbon.
2)Confirm that Snapping is turned off. It should have a white background, not blue.
3)In the Features group, click the Create button
This button opens the Create Features pane on the right of the map. This pane allows you to draw new features in any of the layers marked as editable in the map. By default, all layers are editable, so you will change that so that you don’t accidentally add new rivers, parks, census tracts, and so on.
4)In the Contents pane, click the List By Editing button
This list now displays all the layers with a check box next to each one to define whether they are editable or not.
5)Click to clear all but the Bright Map Notes layers (you will probably have to expand the group layer to confirm that they are checked).
Notice that as you click to clear the other layers, the Create Features pane to the right of the map changes to show only those features that are editable.