.. only:: html .. note:: :class: sphx-glr-download-link-note Click :ref:`here ` to download the full example code .. rst-class:: sphx-glr-example-title .. _sphx_glr_gallery_statistics_hist.py: ========== Histograms ========== Demonstrates how to plot histograms with matplotlib. .. code-block:: default import matplotlib.pyplot as plt import numpy as np from matplotlib import colors from matplotlib.ticker import PercentFormatter # Fixing random state for reproducibility np.random.seed(19680801) Generate data and plot a simple histogram ----------------------------------------- To generate a 1D histogram we only need a single vector of numbers. For a 2D histogram we'll need a second vector. We'll generate both below, and show the histogram for each vector. .. code-block:: default N_points = 100000 n_bins = 20 # Generate a normal distribution, center at x=0 and y=5 x = np.random.randn(N_points) y = .4 * x + np.random.randn(100000) + 5 fig, axs = plt.subplots(1, 2, sharey=True, tight_layout=True) # We can set the number of bins with the `bins` kwarg axs[0].hist(x, bins=n_bins) axs[1].hist(y, bins=n_bins) .. image:: /gallery/statistics/images/sphx_glr_hist_001.png :class: sphx-glr-single-img .. rst-class:: sphx-glr-script-out Out: .. code-block:: none (array([3.0000e+00, 1.4000e+01, 6.9000e+01, 2.7700e+02, 9.6900e+02, 2.5790e+03, 5.8010e+03, 1.0379e+04, 1.5122e+04, 1.7920e+04, 1.7298e+04, 1.3536e+04, 8.6630e+03, 4.6080e+03, 1.8750e+03, 6.4100e+02, 2.0000e+02, 3.7000e+01, 7.0000e+00, 2.0000e+00]), array([ 0.15026293, 0.64387908, 1.13749522, 1.63111136, 2.12472751, 2.61834365, 3.11195979, 3.60557594, 4.09919208, 4.59280822, 5.08642437, 5.58004051, 6.07365665, 6.5672728 , 7.06088894, 7.55450508, 8.04812123, 8.54173737, 9.03535351, 9.52896966, 10.0225858 ]), ) Updating histogram colors ------------------------- The histogram method returns (among other things) a ``patches`` object. This gives us access to the properties of the objects drawn. Using this, we can edit the histogram to our liking. Let's change the color of each bar based on its y value. .. code-block:: default fig, axs = plt.subplots(1, 2, tight_layout=True) # N is the count in each bin, bins is the lower-limit of the bin N, bins, patches = axs[0].hist(x, bins=n_bins) # We'll color code by height, but you could use any scalar fracs = N / N.max() # we need to normalize the data to 0..1 for the full range of the colormap norm = colors.Normalize(fracs.min(), fracs.max()) # Now, we'll loop through our objects and set the color of each accordingly for thisfrac, thispatch in zip(fracs, patches): color = plt.cm.viridis(norm(thisfrac)) thispatch.set_facecolor(color) # We can also normalize our inputs by the total number of counts axs[1].hist(x, bins=n_bins, density=True) # Now we format the y-axis to display percentage axs[1].yaxis.set_major_formatter(PercentFormatter(xmax=1)) .. image:: /gallery/statistics/images/sphx_glr_hist_002.png :class: sphx-glr-single-img Plot a 2D histogram ------------------- To plot a 2D histogram, one only needs two vectors of the same length, corresponding to each axis of the histogram. .. code-block:: default fig, ax = plt.subplots(tight_layout=True) hist = ax.hist2d(x, y) .. image:: /gallery/statistics/images/sphx_glr_hist_003.png :class: sphx-glr-single-img Customizing your histogram -------------------------- Customizing a 2D histogram is similar to the 1D case, you can control visual components such as the bin size or color normalization. .. code-block:: default fig, axs = plt.subplots(3, 1, figsize=(5, 15), sharex=True, sharey=True, tight_layout=True) # We can increase the number of bins on each axis axs[0].hist2d(x, y, bins=40) # As well as define normalization of the colors axs[1].hist2d(x, y, bins=40, norm=colors.LogNorm()) # We can also define custom numbers of bins for each axis axs[2].hist2d(x, y, bins=(80, 10), norm=colors.LogNorm()) plt.show() .. image:: /gallery/statistics/images/sphx_glr_hist_004.png :class: sphx-glr-single-img .. _sphx_glr_download_gallery_statistics_hist.py: .. only :: html .. container:: sphx-glr-footer :class: sphx-glr-footer-example .. container:: sphx-glr-download sphx-glr-download-python :download:`Download Python source code: hist.py ` .. container:: sphx-glr-download sphx-glr-download-jupyter :download:`Download Jupyter notebook: hist.ipynb ` .. only:: html .. rst-class:: sphx-glr-signature Keywords: matplotlib code example, codex, python plot, pyplot `Gallery generated by Sphinx-Gallery `_