CODEWITHSUNDEEP
pythonmatplotlibgraphing
Ariki
Ariki

Reputation: 43

How to space grids linearly for log scale axis in Matplotlibs?

In matplot lib, I want to space out the grids in a linearly spaced order, while the axis scale is logarithmic.

What I want is this: enter image description here

instead of: enter image description here

The code so far is this:

ax.grid(True,  which="major", ls="-")
ax.set_yscale('log')
ax.yaxis.set_major_formatter(StrMethodFormatter('{x:.8f}'))
ax.yaxis.set_minor_formatter(StrMethodFormatter('{x:.8f}'))

Upvotes: 0

Views: 657

Answers (1)

JohanC
JohanC

Reputation: 80339

You can explicitly set the major ticks at the desired positions. Either simply ticks=[2**i for i in range(30] or the more elaborate ticks from the example (these will be close to being evenly-spaced, but not fully). Optionally, the numbers can be displayed with a thousands-separator. The minor ticks that are automatically added by the log scale look very confusing and can be removed.

from matplotlib import pyplot as plt
import numpy as np
from matplotlib.ticker import FixedLocator, StrMethodFormatter, NullFormatter, NullLocator

fig, ax = plt.subplots()
ax.plot(np.exp(10+np.random.normal(0.01, 0.6, 1000).cumsum()))
ax.grid(True,  which="major", ls="-")
ax.set_yscale('log')
ticks = [j * k for j in (1, 1000, 1000000) for k in [3, 6, 12] + [25*2**i for i in range(7)]   ]
ax.yaxis.set_major_locator(FixedLocator(ticks))
ax.yaxis.set_major_formatter(StrMethodFormatter('{x:,.0f}'))
ax.yaxis.set_minor_locator(NullLocator())
#ax.yaxis.set_minor_formatter(NullFormatter())
ax.set_ylim(ymin=2)
plt.tight_layout()
plt.show()

example plot

Upvotes: 1

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