2.4 Creating a Histogram

2.4.1 Problem

You want to view the distribution of one-dimensional data with a histogram.

2.4.2 Solution

To make a histogram (Figure 2.8), use hist() and pass it a vector of values:

Histogram with base graphics (left); With more bins. Notice that because the bins are narrower, there are fewer items in each bin. (right)Histogram with base graphics (left); With more bins. Notice that because the bins are narrower, there are fewer items in each bin. (right)

Figure 2.8: Histogram with base graphics (left); With more bins. Notice that because the bins are narrower, there are fewer items in each bin. (right)

With the ggplot2, you can get a similar result using geom_histogram() (Figure 2.9):

ggplot2 histogram with default bin width (left); With wider bins (right)ggplot2 histogram with default bin width (left); With wider bins (right)

Figure 2.9: ggplot2 histogram with default bin width (left); With wider bins (right)

When you create a histogram without specifying the bin width, ggplot() prints out a message telling you that it’s defaulting to 30 bins, and to pick a better bin width. This is because it’s important to explore your data using different bin widths; the default of 30 may or may not show you something useful about your data.

2.4.3 See Also

For more in-depth information about creating histograms, see Recipes Recipe 6.1 and Recipe 6.2.