How to show negative values in symbol maps

Circles can only have a positive radius – so when you're creating a symbol map or spike map in Datawrapper and you choose a column with negative values as the Size value, Datawrapper lets you know that "Symbols and spikes cannot show negative sizes" and only shows the positive values as symbols.

Like here, where we try to visualize the change in population of Bay Area cities between 2020 and 2023:

Here are three solutions to this problem.

Choose another column for the symbol size

The easiest solution – depending on your data – could be to choose a column with only positive values for the symbol size and communicate the column with the positive and negative values with the size color instead.

Here, the size visualizes the population (which is always a positive number), and the color visualizes the change:

Create a column with absolute values

To show your negative and positive values with symbols, you can add a column where all your negative values are positive (="absolute"). You can do so in e.g. Excel or Google Sheet with the =ABS() formula.

To do so in Datawrapper, go back to step 2: Upload data and click on Add column in the lower right, then click on Calculated column:

A new column appears. Give it a name (e.g. "Absolute change"), and then type in ABS(column_name) in the Formula field, where column_name is the name of your column. You can also click on the column name at the bottom to add it to the formula.

You'll see that all your positive values stay the same, while the negative ones become positive. 

You can now use this freshly calculated column for the symbol size to create a map like that. Make the original column with the negative and positive values show up in the tooltip so that your readers understand what you want to show:

Note that the size legend won't be that helpful anymore, since it only shows the positive values. 

Create an arrow map

Arrow maps are a subtype of symbol maps that can display negative numbers. You'll find them in the symbol map editor right at the top:

Here's how our map looks like if we turn it into an arrow map:

Note that you can't color the arrows according to the values in arrow maps. You can, however, specify a color for all negative and all positive values. 

To learn more about how to create an arrow map and which customization options you have when doing so, head over to this article.