Matplotlib的反转轴、绘制双轴和定制刻度详解

import numpy as np
from matplotlib import pyplot as plt
plt.rcParams['font.sans-serif'] = ['FangSong']
plt.rcParams['axes.unicode_minus'] = False
y, x = np.mgrid[-2:2:200j, -3:3:300j]
z = np.exp(-x**2-y**2) - np.exp(-(x-1)**2-(y-1)**2)
fig = plt.figure()
ax1 = fig.add_subplot(221)
ax2 = fig.add_subplot(222)
ax3 = fig.add_subplot(223)
ax4 = fig.add_subplot(224)
ax1.imshow(z, cmap='jet', origin='lower')
ax2.imshow(z, cmap='jet', origin='lower')
ax3.imshow(z, cmap='jet', origin='lower')
ax4.imshow(z, cmap='jet', origin='lower')
ax2.invert_xaxis()
ax3.invert_yaxis()
ax4.invert_xaxis()
ax4.invert_yaxis()
ax1.set_title("正常的X、Y轴")
ax2.set_title("反转X轴")
ax3.set_title("反转Y轴")
ax4.set_title("反转X、Y轴")
plt.show()

import numpy as np
from matplotlib import pyplot as plt
plt.rcParams['font.sans-serif'] = ['FangSong']
plt.rcParams['axes.unicode_minus'] = False
x = np.linspace(-2*np.pi, 2*np.pi, 200)
y1 = np.square(x)
y2 = np.cos(x)
fig = plt.figure()
ax = fig.add_axes([0.1, 0.1, 0.8, 0.8])
ax_twinx = ax.twinx()
ax.plot(x, y1, c='r')
ax_twinx.plot(x, y2, c='g', ls='-.')
plt.show()

import numpy as np
from matplotlib import pyplot as plt
x = np.linspace(0, 2*np.pi, 100)
y = np.sin(x)
fig = plt.figure()
ax1 = fig.add_subplot(121)
ax1.plot(x, y, c='r')
ax1.set_ylim(-0.8, 0.8)
ax2 = fig.add_subplot(122)
ax2.plot(x, y, c='g')
ax2.set_xlim(-np.pi, 3*np.pi)
plt.show()

import numpy as np
from matplotlib import pyplot as plt
import matplotlib.dates as mdates
x = np.arange('2019-01', '2019-06', dtype='datetime64[D]')
y = np.random.rand(x.shape[0])
fig = plt.figure()
ax = fig.add_axes([0.1, 0.1, 0.8, 0.8])
ax.plot(x, y, c='g')
ax.xaxis.set_major_locator(mdates.MonthLocator())
ax.xaxis.set_major_formatter(mdates.DateFormatter('\n%Y-%m-%d'))
ax.xaxis.set_minor_locator(mdates.DayLocator(bymonthday=(1,11,21)))
ax.xaxis.set_minor_formatter(mdates.DateFormatter('%d'))
plt.show()

import numpy as np
from matplotlib import pyplot as plt
from matplotlib.ticker import MultipleLocator
plt.rcParams['font.sans-serif'] = ['FangSong']
plt.rcParams['axes.unicode_minus'] = False
x = np.linspace(0, 4*np.pi, 500)
fig = plt.figure()
ax1 = fig.add_subplot(121)
ax1.plot(x, np.sin(x), c='m')
ax1.yaxis.set_major_locator(MultipleLocator(0.3))
ax2 = fig.add_subplot(122)
ax2.plot(x, np.sin(x), c='m')
ax2.xaxis.set_major_locator(MultipleLocator(3))
ax2.xaxis.set_minor_locator(MultipleLocator(0.6))
ax1.set_title('X轴刻度自动调整，Y轴设置刻度间隔0.3')
ax2.set_title('X轴设置主刻度间隔3副刻度间隔0.6，Y轴刻度自动调整')
plt.show()

import numpy as np
from matplotlib import pyplot as plt
import matplotlib.dates as mdates
x = np.arange('2019-01', '2020-01', dtype='datetime64[D]')
y = np.random.rand(x.shape[0])
fig = plt.figure()
ax = fig.add_axes([0.1, 0.3, 0.8, 0.6])
ax.plot(x, y, c='g')
ax.xaxis.set_major_locator(mdates.MonthLocator())
ax.xaxis.set_major_formatter(mdates.DateFormatter('%Y/%m/%d'))
for lobj in ax.get_xticklabels():
    lobj.set_rotation(35)
    lobj.set_size(12)
    lobj.set_color('blue')
plt.show()

import numpy as np
from matplotlib import pyplot as plt
from matplotlib.ticker import FuncFormatter
plt.rcParams['font.sans-serif'] = ['FangSong'] # 设置字体以便正确显示汉字
plt.rcParams['axes.unicode_minus'] = False # 正确显示连字符
x = np.linspace(0, 10, 200)
y = np.square(x)
def func_x(x, pos):
    return '%0.2f秒'%x
def func_y(y, pos):
    return '%0.2f°C'%y
formatter_x = FuncFormatter(func_x)
formatter_y = FuncFormatter(func_y)
fig = plt.figure()
ax = fig.add_axes([0.1, 0.1, 0.8, 0.8])
ax.plot(x, y, c='r')
ax.xaxis.set_major_formatter(formatter_x)
ax.yaxis.set_major_formatter(formatter_y)
plt.show()