Building a map of intersections
I continue by opening the violations dataset in Tableau:
- Longitude and latitude values are not automatically recognized, so I have to change both to Number (decimal) by clicking on the data type icon:
Figure 12.41: Change data type
- Then, I change the Longitude and Latitude fields to Measure by clicking on the drop-down arrow on the field as shown in the preceding figure and selecting Convert to Measure.
- Now I can click on the data type icon again and change the two fields to Latitude and Longitude:
Figure 12.42: Changing the geographic role
- By dragging Longitude to Columns, Latitude to Rows, and Intersection to the Text shelf, I visualize the red-light locations—at least the ones that have ever had a violation:
Figure 12.43: Intersections in Chicago
- The name of the worksheet will be
Intersection, and since I am looking at violations, I change the color...