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Merge pull request #7800 from phobson/doc-imshow-logscale
DOC: explain non-linear scales and imshow (closes #7661)
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doc/users/whats_new.rst

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@@ -212,6 +212,48 @@ setting the private member ``_image_skew_coordinate`` has been
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removed. Instead, images will obey the transform of the axes on which
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they are drawn.
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Non-linear scales on image plots
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````````````````````````````````
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:func:`imshow` now draws data at the requested points in data space after the
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application of non-linear scales.
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The image on the left demonstrates the new, correct behavior.
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The old behavior can be recreated using :func:`pcolormesh` as
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demonstrated on the right.
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Non-linear scale example
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````````````````````````
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.. plot::
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import numpy as np
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import matplotlib.pyplot as plt
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data = np.arange(30).reshape(5, 6)
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x = np.linspace(0, 6, 7)
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y = 10**np.linspace(0, 5, 6)
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X, Y = np.meshgrid(x, y)
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fig, (ax1, ax2) = plt.subplots(ncols=2, figsize=(8, 4))
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ax1.imshow(data, aspect="auto", extent=(0, 6, 1e0, 1e5), interpolation='nearest')
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ax1.set_yscale('log')
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ax1.set_title('Using ax.imshow')
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ax2.pcolormesh(x, y, np.flipud(data))
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ax2.set_yscale('log')
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ax2.set_title('Using ax.pcolormesh')
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ax2.autoscale('tight')
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plt.show()
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This can be understood by analogy to plotting a histogram with linearly spaced bins
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with a logarithmic x-axis. Equal sized bins will be displayed as wider for small
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*x* and narrower for large *x*.
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Support for HiDPI (Retina) displays in the NbAgg and WebAgg backends
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