Once you have the basics of creating and editing a map down, filters are the next step for increasing your mastery in mySidewalk. Not every map needs filters, but they are handy tools that can increase the detail and information you are able to display in a map.
- Limit the area shown in your map to where you’re most interested by showing specific parts of a variable, like only census tracts with low access to cars in a layer about low access to healthy food
- Add information that gives each sub-geography in your map more detail or context by adding more information about a variable; for example, adding specific disabilities to a map showing percent of residents with a disability
- Show the original data that has been normalized, or made into a percent.
To add filters to a layer you’ve created, click Filters next to Style in the edit panel. From here, you have two options:
- Select a dataset: Choose a dataset other than the one visualized.
- Add a filter: Add a filter for the dataset visualized in your layer.
No matter which you choose, your options for editing the filter will be the same.
Once you have added your filter layer, starting from the top of the filter menu:
- The eye icon above the Change Data button will turn your filter on or off.
- Change Data will enable you to pick a different dataset for the filter. This button is followed by the name of the current dataset in the filter, and then the source of the data.
Under More Options, you can:
- Change the label of the filter. This label shows up when clicking on the map.
- Normalize the data.
- Change the unit. Remember to edit the unit if you normalize the data!
- Change the format.
- Change the number of decimal places.
The Value Range tells you the minimum and maximum values of the filter’s data within the map layer’s geography (such as a city).
Right under this is Filter Type. Filter Type has two options: value and percentile.
- Value simply uses the original data values from the dataset.
- Percentile will assign each sub-geography a number between 0 and 100. Percentile is most useful when creating filter conditions.
- Even if the Filter Type is set to percentile, the true data value will still show up when you click on the map.
- The lowest data value will be assigned to 0, and the highest will be assigned to 100. Every value between the two will be given a percentile based on where it falls between the lowest and highest values.
Using Filter Conditions:
- Filter conditions allow you to set how your filter will be applied to the layer. It will use the Filter Type (value or percentile) to pick out which sub-geographies the filter will be applied.
- Use the drop-down window to select whether you want the sub-geographies that show up in your map to meet every condition or at least one. For example, one condition may be to show only census tracts with values in the bottom 25%. Another condition may be to show only census tracts with values in the top 25%. A census tract can only satisfy one of these conditions at a time, so you would want to set the dropdown to select ‘Geographies must meet ANY conditions.’
- To turn off a condition, click on the eye icon on the right. Click it again to turn it back on. This can help you see what impact the condition has on the layer.
- Has Any Value: Great for simply adding information to your map.
- Has No Value: Restricts the map to areas that have no assigned value for the filter’s dataset.
- Range: Restricts the map to areas by minimum and maximum values you choose.
- Between: Restricts the map to areas with values between the minimum and maximum values you choose. The big difference in Between and Range is that in a map where you select Between, the minimum and maximum are not included in the data selection. The selection of data Between two numbers only includes the numbers above the minimum and below the maximum, not the minimum and maximum themselves.
- At least: Restricts the map to areas with a value equal to or greater than the value you choose.
- At most: Restricts the map to areas with a value equal to or less than the value you choose.
- Greater than: Restricts the map to areas with a value greater than the value you choose.
- Less than: Restricts the map to areas with a value less than the value you choose.
- Equal: Restricts the map to areas that exactly match the value you choose.
- Not equal: Restricts the map to areas that do not match the value you choose.
When you’re done making changes to your filter, click Done above or below the filter editing boxes.
For further explanation, check out the video below!
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