Map Extent

Updated by PolicyMap

The Map Extent feature allows users see how data layers ranges are represented locally. The default cut points for ranges are for the national range, so the map extent changes the data range for just the area they are viewing within the window.

To start, users must have a data layer with a range of values loaded, so no yes/no layer (eligibility) or categorial data layers. Select the Map Extent button in the legend and by default the range of will adjust based on the range available in the current map window (the extent). This will adjust your color ranges and values they represent in the legend.

animation of map extent

For example, median home sales prices for the San Jose area all fall within the $412,000 or greater range (from the national average which starts at $10,000 to $8,750,000) due to the high cost of housing in the Bay Area. If we select the Map Extent, the ranges adjust to show that based the extent the new ranges start at $708,000 and maxes at $6,401,500. The new color ranges show that houses in San Jose are $1,200,000 or less while houses in Cupertino and Palo Alto are over $2,499,501.

animation of map extent of home sales

Another example is how many persons speak Spanish at home in the San Jose area. The national range shows that most tracts have more than 1% with a few spots more than 19%. If we select Map Extent, we see that most tracts have more than 4% and many tracts with more than 31% speaking Spanish.

animation of map extent spanish speaking

Map Extent can also be determined by the selection location or custom region. This allows users to see the layer ranges represented just for the location.

To start for a selected location, search for a place in the Location Bar. Open the Info Bubble for the location and select the Clip button. (please read the guide for Clip to learn of the feature)

Add a data layer, and the map will show the national range be default but select Map Extent will show the range just for the location. This unique view lets users see how the data layer represents the area locally.

animation of clipped map extent

The same clip button is available for the custom region info bubble too.

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