Plot Geo: fill by color channel domain

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1

I am using Plot Geo and am trying to sync the state party color domain with the total count of legislative bills per US state. I have a BarY chart above that represents the dataset with the color channel domain/range defined. When I add the same domain/range (commented out) to the Plot Geo there is no fill…

The end result should be for example - if the topic guns is selected - TN should be red and the darkest value compared to AK. Likewise, NY should be the darkest blue value compared to OR

Any help will be appreciated. Thanks.

2

When you group with Plot.groupZ() by z: "state", you have to set the correct reducer (–> how to aggregate within each group)

  • in your code, the reducer was fill:"count" which is what you want for a quantitative scale. But now you changed the domain to expect state names instead (not integers). That’s why the color scale could not compute a color.

  • So you have to change the reducer to fill:"first" and also add to the input the referenced column fill:"state". Now Plot knows to apply the aggregation "first" to the column "state" (pick the first element of the array of elements of this group)


    Plot.geo(
      flat_class,
      Plot.groupZ(
        {
          fill: "first",
          geometry: ([state]) =>
            states.features.find((d) => d.properties.name === state)
        },
        {
          geometry: "state",
          z: "state",
          fill: "state",
          title: (d) => d.identifier
        }
      )
    ),

See OpenStates export test / ee2dev | Observable.

P.s you don’t need to hard code the domain and range to replicate a scale from another plot. Instead, you can assign the previous Plot to a named cell and then reference its scale by …plot.scale(„color“) to access its domain and range.

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