Histograms are useful for visualizing distributions between multiple categorical features and for simplifying visualizations of multiple numerical features.
Histogram plots contain bins. Each bin represents a particular category for each dimension (for categorical features) or a particular range (for numerical features). You can see what categories or ranges are contained in a bin by looking at the tick marks (the labels surrounding the plot box), or by clicking on the bin. By default, the size of the bin and the color show how many points fall into that bin’s range, but size and color can also be used to visualize additional features.
Required Features and Dimensions
Histogram plots require at least one feature mapped to any positional dimension. Any numerical or categorical features can be used, and up to 100 categories will be shown on the tickmarks for each axis. The maximum number of bins on any axis is 1,000, and there is a maximum of 1,000,000 bins across all axes.
Histogram settings, found in the Plot Settings of the Mapping panel, allow you to change the number of bins that are shown for numerical features. For categorical features, the number of bins is locked to the number of unique categories in the feature.
At the top of the Input tab, there are also options to change what the size of each bin (height for 1D or 2D histograms, volume for 3D histograms) represents — either the count of the points that fall into each bin range, or a uniform size for each bin. If a feature is mapped to Size, the size of the bin can also represent either the average value or the sum of values of the feature mapped to Size for all points within that bin.