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- In the Contents pane, right-click the Census_2010_By_SuperNeighborhood layer name and selectSymbology.
- Use the primary 'Symbology' drop-down menu to selectGraduated Colors.
- Use the 'Field' drop-down menu to scroll down sixth from the bottom and select the SUM_Vacant field. This field stores the number of vacant housing units within each neighborhood.
The map view now displays a choropleth map, where the darker colors represent higher numbers of vacant housing units. In studying the map, it appears as if the most vacant housing is in southwest Houston outside the Loop. While this is true according to raw counts per neighborhood, there could be differences in the neighborhoods that are unaccounted for in this symbology. Now you will try normalizing by the area of the neighborhood. - Use the 'Normalization' drop-down menu to scroll to the bottom and select the last Shape_Area field.
As discussed in the Introduction to GIS Data Management course, the projection of the census layer is WGS 1984. Therefore, the layer is unprojected and the coordinates are stored in angular units of decimal degrees. Therefore, the Shape_
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- Area field is displaying square decimal degrees and the map is displaying number of vacant housing units per square decimal degree. This is a somewhat
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- incomprehensible unit, however, the values are still proportional to how they would be in a different unit and the relative coloring on the map remains correct
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- .
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- Notice that according to the density of vacant housing units, the greatest amount of vacant housing units appear to be both inside and outside the loop along 59.
- Use the 'Normalization' drop-down menu to select the SUM_HU100 field.
The map is now displaying the number of vacant housing units divided by the total number of housing units, or the percent vacant housing units. While
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- both methods of symbolizing the vacant housing units are
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- technically correct, this is probably the most common method.
- On the lower half of the Symbology pane, click the Histogram tab.
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Discuss and test classification methods.
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- Use the 'Method" drop-down menu to select Equal Interval.
- Use the 'Method" drop-down menu to select Quantile.
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Discuss and test number of classes.
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- Use the 'Classes' drop-down menu to select 20.
- Use the 'Classes' drop-down menu to select 4.
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Discuss and test color schemes.
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Adding Layer Transparency
- Ensure that the Census_2010_By_SuperNeighborhood layer is selected.
- In the ribbon, click the Feature Layer contextual Appearance tab.
- In the Effects group, slide the Layer Transparency slider or type "50" and hit Enter.
Symbolizing Layers By Category
- Use the primary 'Symbology' drop-down menu to select Unique Values.
- Use the 'Field 1' drop-down menu to select Name.
- In the Contents pane, collapse the Census_2010_By_Superneighborhood symbology.
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zoom into neighborhood, go to explore button, click on neighborhood to find out neighborhood name.
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- Use the 'Method" drop-down menu to select Equal Interval.
Notice how the map changes. Equal Interval divides the range of attribute values into equal-sized subranges. - Use the 'Method" drop-down menu to select Quantile.
Again, the display of data on the map changes. Quantile assigns the same number of data values to each class. - Use the 'Classes' drop-down menu to select 20.
- Use the 'Classes' drop-down menu to select 4.
Observe how changing the number of classes alters the display. - Use the 'Color Scheme' drop-down menu to select a different color scheme of your choice.
Adding Layer Transparency
- Ensure that the Census_2010_By_SuperNeighborhood layer is selected.
- In the ribbon, click the Feature Layer contextual Appearance tab.
- In the Effects group, slide the Layer Transparency slider or type "50" and hit Enter.
- Return the Layer Transparency slider to "0".
Symbolizing Layers By Category
- Use the primary 'Symbology' drop-down menu to select Unique Values.
- Use the 'Field 1' drop-down menu to select Name.
- In the Contents pane, collapse the Census_2010_By_Superneighborhood symbology.
Selecting Features Programatically
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