Update key to match colors displayed in map

[JonellaCulmer]

What we're after: As part of the improvements needed prior to the WCCF feature release, the key needs to be updated to accurately match the colors shown in the map for each candidate/election year. This is specific to states with money. At this time, we will not include a color category for states that are colored "white" and have no funds to display.

Completion criteria:

• Update key to automatically display all applicable colors shown in the map for a given candidate/election year

Screenshot

[rfultz]

After investigating deeper yesterday, some discoveries:

• The current map ("Individual contributions" section, "State" button/tab) has the same issue.

• The states and legend are using the same color scale.

• Though they're sometimes very close, none of the states are the same color as any other state.*

• The color scale is a kind of number line with the smallest value on the left being represented with the lightest color and the highest value on the right being represented by the darkest color.

• States' colors are chosen based on where their value would put them on that number line.

• The legend reflects the colors at specific milestones along the scale—each quantile will be its corresponding color without regard to any of the states' individual values. (e.g., if the range of values can be divided neatly into quantiles of $10M, we'll have markers at $20M, $30M, and $40M even if there are no states at the same place on the number line. The legend colors will be chosen based on where $20M, $30M, and $40M fall on the number line.)

*They could be if their value's position on the scale were the same as another state's. e.g., if two states were exactly 5.678% of the way between the minimum and maximum value of the scale, they would be exactly the same color.

Next Steps

After discussing with @patphongs and @JonellaCulmer yesterday, we've decided to corral the states' colors to fit into the legend's selected colors. (i.e., states' colors will be "rounded" to the next highest legend color.)

We don't currently plan to apply the updated functionality to the existing map.