Martín González

Visual journalist, designer, map maker.

Where did the Basque Socialists lost 40% of the vote?

Before the latest Basque parliamentary election took place I started working in an explainer. After seeing the election unfold the story was much clearer: the Socialist Party lost 40% of the vote. So we decided to focus on them.

Tools: D3.js, R. With Jorge Galindo.

Go to the interactive
Socialist loss between 2016 and 2009 in each city. Note the log scale in the y axis.

The bar chart

After sketching several charts in ggplot I settled down on a map, a scatterplot and a bar chart. I tried to simplify the bar chart axes as much as I could, thinking about small things as the vertical lines that go along the chart. I also added an arrow to mark the difference between losing and winning votes.

Another small detail is the city label color. When the bars have a dark fill it’s white, but it switches to black when the background is lighter.

First sketch of the bar chart in ggplot.
Final design.

Scatterplot

The scatterplot was more complicated. First, I used a log scale to dissipate differences between city sizes. Then I implemented a voronoi diagram to make the tooltip seamless. While a normal voronoi would trigger the tooltip at any distance from the nearest circle, I used a limited distance voronoi, which only triggers a mouse event when the user hovers near a circle.

First sketch with ggplot.

I made other small decisions. There are some dots that suffer from occlusion. To be able to distinguish them while hovering I drew the border of the selected circle again, on top.

The map

The map opens the piece and is crucial to understand the spatial angle of the story: the Socialists lost most of the vote in the biggest cities. It has a heavy annotation layer.