How to create a swing arrow map

Swing maps are a great way to visualize changes in electoral behavior. They show the extent of change in voter support, typically from one election to another, expressed as a positive or negative percentage.

Flourish enables you to quickly and easily create your own swing arrow map using our Projection map template by following the steps below.

1

Select our swing arrow map starting point.

2

In the Points sheet of the Data tab, upload your data. It should have longitude and latitude columns, as well as a Size by column and, optionally, a Color by column.

TIP: Make sure you have some negative and some positive values in your data. Negative values will point left, positive values will point right.

You can also supply different metrics to display within a dropdown or filter by adding multiple to the Size by column.

3

In the Data tab, navigate to the Points layer settings. Here you can define:

• The arrow angle in degrees: This sets the angle clockwise for positive values (between 0 and 180)
• The minimum length in pixels: This sets the minimum length (lower range) of arrows
• The maximum length in pixels: This sets the max length (upper range) of arrows
• The arrow flip mode, choosing from vertical and horizontal: This sets how the negative-valued arrows are flipped. If vertically, then the negative arrow angle is the negative value of the positive arrow angle (a 60 degree arrow becomes -60 degrees). If horizontally, the angle is 180 minus the positive angle (a 60 degree arrow becomes 120 degrees). Defaults to vertical. 
• The maximum value: Values bigger than this maximum will have a length equal to the maximum length set. To use the maximum in the dataset, leave this setting blank. 
• The fill opacity
• The stroke width, opacity and color

4

You can also change how the arrows are colored.

If Color by value is enabled, the arrows are colored depending on whether their values are positive or negative. You can set the colours manually for both. Otherwise, arrows are coloured by the Points > Color by column (if set) or a customizable default fill.

5

Finally, you might want to tweak your legend to set the positive and negative labels and adjust the height of the arrow icons. You can do this in the Legend > Arrow legend settings.