Setting both axes logarithmic in bar plot matploblib
Solution 1
By default, the bars of a bar
plot have a width of 0.8. Therefore they appear larger for smaller x values on a logarithmic scale. If instead of specifying a constant width, one uses the distance between the bin edges and supplies this to the width
argument, the bars will have the correct width. One would also need to set the align
to "edge"
for this to work.
import matplotlib.pyplot as plt
import numpy as np; np.random.seed(1)
x = np.logspace(0, 5, num=21)
y = (np.sin(1.e-2*(x[:-1]-20))+3)**10
fig, ax = plt.subplots()
ax.bar(x[:-1], y, width=np.diff(x), log=True,ec="k", align="edge")
ax.set_xscale("log")
plt.show()
I cannot reproduce missing ticklabels for a logarithmic scaling. This may be due to some settings in the code that are not shown in the question or due to the fact that an older matplotlib version is used. The example here works fine with matplotlib 2.0.
Solution 2
If the goal is to have equal width bars, assuming datapoints are not equidistant, then the most proper solution is to set width as
plt.bar(x, y, width=c*np.array(x), color='b', log=True)
for a constant c
appropriate for the plot. Alignment can be anything.
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Updated on September 15, 2022Comments
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I have already binned data to plot a histogram. For this reason I'm using the
plt.bar()
function. I'd like to set both axes in the plot to a logarithmic scale.If I set
plt.bar(x, y, width=10, color='b', log=True)
which lets me set the y-axis to log but I can't set the x-axis logarithmic. I've triedplt.xscale('log')
unfortunately this doesn't work right. The x-axis ticks vanish and the sizes of the bars don't have equal width.I would be grateful for any help.