Python matplotlib：设置主要和次要刻度强制相同的 x 和 y 比例

matplotlib: Setting both major and minor ticks forces same x and y scale

提问by owl

This question is related to the earlier question I asked "matplotlib: Change grid interval and specify tick labels" but now I want to change the scale for x and y axes. When I set the range for x and y axes and then specify the intervals for major and minor ticks, it forces the x and y axes to be the same.

这个问题与我之前问过的问题“ matplotlib：更改网格间隔并指定刻度标签”有关，但现在我想更改 x 和 y 轴的比例。当我设置 x 和 y 轴的范围，然后指定主要和次要刻度的间隔时，它会强制 x 和 y 轴相同。

This is my code.

这是我的代码。

import matplotlib.pyplot as plt
import numpy as np

fig = plt.figure()
ax = fig.add_subplot(111)

for key, value in sorted(data.items()):
    x = value[0][2]
    y = value[0][3]
    count = value[0][4]

    ax.annotate(count, xy = (x, y), size = 3)

plt.suptitle('Number of counts', fontsize = 12)

ax.set_xlabel('x')
ax.set_ylabel('y')
ax.set_aspect('equal')

# I want max x axis to be 500
ax.set_xlim(0, 501)
# I want max y axis to be 300
ax.set_ylim(0, 301)

# I want major ticks to be every 20
major_ticks = np.arange(0, 501, 20)

# I want minor ticks to be every 5
minor_ticks = np.arange(0, 501, 5)
# If I do minor_ticks = np.arange(0, 301, 5), I will not get minor ticks for the entire plot

# Specify tick label size
ax.tick_params(axis = 'both', which = 'major', labelsize = 4)
ax.tick_params(axis = 'both', which = 'minor', labelsize = 0)
# Suppress minor tick labels

ax.set_xticks(major_ticks)
ax.set_xticks(minor_ticks, minor = True)
ax.set_yticks(major_ticks)
ax.set_yticks(minor_ticks, minor = True)

# Set both ticks to be outside
ax.tick_params(which = 'both', direction = 'out')

# Specify different settings for major and minor grids
ax.grid(which = 'minor', alpha = 0.3)
ax.grid(which = 'major', alpha = 0.7)

filename = 'C:\Users\Owl\Desktop\Plot.png'
plt.savefig(filename, dpi = 150)
plt.close()

and this is what I get.

这就是我得到的。

How could I get different ranges for x and y axes and still have major and minor ticks like this? I might be missing something very simple but if somebody could point it out, I am very thankful for that!!

我怎样才能获得 x 和 y 轴的不同范围，并且仍然有这样的主要和次要刻度？我可能遗漏了一些非常简单的东西，但如果有人能指出来，我非常感谢！！

采纳答案by BrenBarn

That's because you set the x and y ticks to the same thing. If you want different sizes, then you also need different ticks. You can't set both sets of ticks to the same major_tickspositions. Make one list of tick positions for the x axis and a separate list of tick positions for y axis and then set the ticks for each axis to the corresponding list.

那是因为您将 x 和 y 刻度设置为相同的值。如果您想要不同的尺寸，那么您还需要不同的刻度。您不能将两组刻度设置到相同的major_ticks位置。为 x 轴制作一个刻度位置列表，为 y 轴制作一个单独的刻度位置列表，然后将每个轴的刻度设置为相应的列表。

回答by owl

I updated my code as below and now I get what I wanted! Thanks!

我更新了我的代码如下，现在我得到了我想要的！谢谢！

import matplotlib.pyplot as plt
import numpy as np

fig = plt.figure()
ax = fig.add_subplot(111)

for key, value in sorted(data.items()):
    x = value[0][2]
    y = value[0][3]
    count = value[0][4]

    ax.annotate(count, xy = (x, y), size = 3)

plt.suptitle('Number of counts', fontsize = 12)

ax.set_xlabel('x')
ax.set_ylabel('y')
ax.set_aspect('equal')

# I want max x axis to be 500
ax.set_xlim(0, 501)
# I want max y axis to be 300
ax.set_ylim(0, 301)

# Set major ticks for x axis
major_xticks = np.arange(0, 501, 20)

# Set major ticks for y axis
major_yticks = np.arange(0, 301, 20)

# I want minor ticks for x axis
minor_xticks = np.arange(0, 501, 5)

# I want minor ticks for y axis
minor_yticks = np.arange(0, 301, 5)

# Specify tick label size
ax.tick_params(axis = 'both', which = 'major', labelsize = 6)
ax.tick_params(axis = 'both', which = 'minor', labelsize = 0)
# Suppress minor tick labels

ax.set_xticks(major_xticks)
ax.set_xticks(minor_yticks, minor = True)

ax.set_yticks(major_xticks)
ax.set_yticks(minor_yticks, minor = True)

# Set both ticks to be outside
ax.tick_params(which = 'both', direction = 'out')

# Specify different settings for major and minor grids
ax.grid(which = 'minor', alpha = 0.3)
ax.grid(which = 'major', alpha = 0.7)

filename = 'C:\Users\Owl\Desktop\Plot.png'
plt.savefig(filename, dpi = 150)
plt.close()