A heat chart is used to visualize the numeric relationship between two categorical variables. A heat chart consists of a rectangular grid composed of two categorical variables. Each cell in the grid is symbolized using a numeric value.
Heat charts can help you answer questions about your data, such as: How are numeric values distributed or summarized by two categories? How are two categories related?
A crime analyst is studying the frequency of theft-related crimes in her city. She wants to know the type of incident occurring most often and the months that have the most crime. A heat map can be used to visualize the relative prevalence of each crime for each month.
Create a heat chart
To create a heat chart, complete the following steps:
- Select one of the following combinations of data:
- Two string fields
- Two string fields plus a number or rate/ratio field
If you do not select a number or rate/ratio field, your data will be aggregated and a count will be displayed.
You can search for fields using the search bar in the data pane.
- Create the heat chart using the following steps:
- Drag the selected fields to a new card.
- Hover over the Chart drop zone.
- Drop the selected fields on Heat Chart.
You can also create charts using the Chart menu above the data pane or the Visualization type button on an existing card. For the Chart menu, only charts that are compatible with your data selection will be enabled. For the Visualization type menu, only compatible visualizations (including maps, charts, or tables) will be displayed.
Heat charts can also be created using View Heat Chart, which is accessed from the Action button under Find answers > How is it distributed?.
Heat charts are symbolized using graduated colors.
The Legend button opens the Layer options pane. The Layer options pane contains the following functions:
- The Legend tab can be used to make selections on the chart. The pop out legend button displays the legend as a separate card on your page.
- The Options tab changes the classification type and number of classes.
- The Style tab changes the color palette and outline color.
When you create a heat chart, a result dataset with the string and number fields used to create the chart will be added to the data pane. The result dataset can be used to find answers with nonspatial analysis using the Action button .
The heat chart variables cannot exceed 3,000 unique values per axis. If one or both of the variables exceed the 3,000 value limit, a filter, such as a predefined filter, can be used to reduce the size of the dataset.