Contour

2D density contours. It sits in the Correlation group of the widget library.

When to use it#

Use a contour chart to show where pairs of numbers concentrate as smooth, nested regions, like a topographic map. For example, plot transaction amount against day of the month to see typical spending bands. Darker areas hold more points.

When to pick something else#

• Exact counts per region? Use a Hexbin.
• Few points, or individual points that matter? Use a Scatter plot.
• The spread of a single number? Use a Density or Histogram.

The data it needs#

Pick these in the Data tab of the inspector. BankSync suggests a column for each when your source has an obvious match.

Each row is drawn as it is, so shape the rows first if you need totals. See Shaping data.

Contour options#

This chart has no options of its own; everything on its Style tab is the shared chart styling below.

Shared chart styling#

Every chart also has the shared styling options. These apply to this one:

• Legend: position, layout and which series show.
• Axes: titles, tick labels and number format.
• Grid, title, padding and background.
• Value labels on the marks.
• Categories and labels: top N with "Other", sort order, readable labels, the handwritten callout.
• Style: corner radius, line width, opacity and animation.
• Tooltip on hover.
• Colours: follow the dashboard palette or pick one for this chart.

Messy data#

• Both fields must be numbers. Rows where either is blank, text or a date are skipped. If nothing remains you see "No numbers to show".
• Fewer than ten points are drawn as plain dots, since contours from so few points would be misleading.
• The shading shows relative density ("percent of peak"), not amounts or counts.
• Very large tables are sampled evenly before the shape is estimated.
• Outliers stretch the axes and squash the dense region into a small area. Filter them out first.

On a phone#

On a phone the contours smooth over a proportionally wider area and fewer levels are drawn on a shorter card, so the shape reads as a softer blob. The colour key sits under the plot while there is room.

Related charts#

• Bubble chart: Scatter sized by a field
• Hexbin: Binned 2D density
• Parallel coordinates: Multi-dimensional comparison