### Navigation

- index
- modules |
- home|
- examples|
- tutorials|
- pyplot|
- docs »

# Building histograms using Rectangles and PolyCollections

This example shows how to use a path patch to draw a bunch of rectangles. The technique of using lots of Rectangle instances, or the faster method of using PolyCollections, were implemented before we had proper paths with moveto/lineto, closepoly etc in mpl. Now that we have them, we can draw collections of regularly shaped objects with homogeneous properties more efficiently with a PathCollection. This example makes a histogram – its more work to set up the vertex arrays at the outset, but it should be much faster for large numbers of objects

    import numpy as np
    import matplotlib.pyplot as plt
    import matplotlib.patches as patches
    import matplotlib.path as path

    fig, ax = plt.subplots()

    # Fixing random state for reproducibility
    np.random.seed(19680801)

    # histogram our data with numpy

    data = np.random.randn(1000)
    n, bins = np.histogram(data, 50)

    # get the corners of the rectangles for the histogram
    left = np.array(bins[:-1])
    right = np.array(bins[1:])
    bottom = np.zeros(len(left))
    top = bottom + n

    # we need a (numrects x numsides x 2) numpy array for the path helper
    # function to build a compound path
    XY = np.array([[left, left, right, right], [bottom, top, top, bottom]]).T

    # get the Path object
    barpath = path.Path.make_compound_path_from_polys(XY)

    # make a patch out of it
    patch = patches.PathPatch(barpath)
    ax.add_patch(patch)

    # update the view limits
    ax.set_xlim(left[0], right[-1])
    ax.set_ylim(bottom.min(), top.max())

    plt.show()

Total running time of the script: ( 0 minutes 0.032 seconds)

Generated by Sphinx-Gallery