# 等高线标签演示

说明一些可以用等高线的标签做的更高级的东西。

另请参见轮廓演示示例

import matplotlib
import numpy as np
import matplotlib.ticker as ticker
import matplotlib.pyplot as plt

定义我们的外观

delta = 0.025
x = np.arange(-3.0, 3.0, delta)
y = np.arange(-2.0, 2.0, delta)
X, Y = np.meshgrid(x, y)
Z1 = np.exp(-X**2 - Y**2)
Z2 = np.exp(-(X - 1)**2 - (Y - 1)**2)
Z = (Z1 - Z2) * 2

使用创造性的浮动类制作等高线的标签,遵循曼纽尔·梅茨的建议。

# Define a class that forces representation of float to look a certain way
# This remove trailing zero so '1.0' becomes '1'


class nf(float):
    def __repr__(self):
        str = '%.1f' % (self.__float__(),)
        if str[-1] == '0':
            return '%.0f' % self.__float__()
        else:
            return '%.1f' % self.__float__()


# Basic contour plot
fig, ax = plt.subplots()
CS = ax.contour(X, Y, Z)

# Recast levels to new class
CS.levels = [nf(val) for val in CS.levels]

# Label levels with specially formatted floats
if plt.rcParams["text.usetex"]:
    fmt = r'%r \%%'
else:
    fmt = '%r %%'

ax.clabel(CS, CS.levels, inline=True, fmt=fmt, fontsize=10)

等高线标签演示示例

使用字典用任意字符串标记等高线

fig1, ax1 = plt.subplots()

# Basic contour plot
CS1 = ax1.contour(X, Y, Z)

fmt = {}
strs = ['first', 'second', 'third', 'fourth', 'fifth', 'sixth', 'seventh']
for l, s in zip(CS1.levels, strs):
    fmt[l] = s

# Label every other level using strings
ax1.clabel(CS1, CS1.levels[::2], inline=True, fmt=fmt, fontsize=10)

等高线标签演示示例2

使用Formatter来格式化

fig2, ax2 = plt.subplots()

CS2 = ax2.contour(X, Y, 100**Z, locator=plt.LogLocator())
fmt = ticker.LogFormatterMathtext()
fmt.create_dummy_axis()
ax2.clabel(CS2, CS2.levels, fmt=fmt)
ax2.set_title("$100^Z$")

plt.show()

等高线标签演示示例3

# 参考

本例中显示了以下函数、方法和类的使用:

matplotlib.axes.Axes.contour
matplotlib.pyplot.contour
matplotlib.axes.Axes.clabel
matplotlib.pyplot.clabel
matplotlib.ticker.LogFormatterMathtext
matplotlib.ticker.TickHelper.create_dummy_axis

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