Matplotlib 3D 绘图，如何正确使用 set_zlim() [英] Matplotlib 3D plot, How to use set_zlim() correctly

问题描述

我有多个情节.我想设置 Z lim 使其仅显示指定范围内的曲线.我的代码在这里

I have multiple plot. I want to set Z lim such that it only shows the curve within the specified range. My code here

# make 3d axes
fig = plt.figure()
ax = fig.gca(projection='3d')

# test data
x = np.arange(-1., 1., .1)
y = np.arange(-1., 1., .1)
z1 = x**2
z2 = x**3
z3 = x**4

# plot test data
ax.plot(x, np.ones(len(x)), z1)
ax.plot(x, np.ones(len(x))*3, z2)
ax.plot(x, np.ones(len(x))*5, z3)

# make labels
ax.set_xlabel('X')
ax.set_ylabel('Y')
ax.set_zlabel('Z')
ax.set_zlim(0)
plt.show()

显示我希望图中只显示 Z2 的正部分，但它显示了所有曲线并使绘图更加混乱.

Shows I'm expecting that only the positive part of Z2 shown on the graph but it shows all the curves and make the plot messier.

推荐答案

您可以在绘制之前使用 MaskedArray 过滤不需要的数据.解决办法如下:

You can use MaskedArray to filter un-wanted data before plotting. Here is the solution:

from mpl_toolkits.mplot3d import Axes3D
import matplotlib.pyplot as plt
import numpy as np
import numpy.ma as ma

fig = plt.figure(figsize=[8,7])
ax = fig.gca(projection='3d')

# test data
x = np.arange(-1., 1., .1)
y = np.arange(-1., 1., .1)
z1 = x**2
z2 = x**3
z3 = x**4

# masking the data (take `z2` as the base)
z2m = ma.masked_less_equal(z2, 0, copy=True)
y2 = np.ones(len(x))*3

# applying the mask to corresponding `x` and `y`
x2m = ma.MaskedArray(x, mask=z2m.mask)
y2m = ma.MaskedArray(y2, mask=z2m.mask)

# we get (x2m, y2m, z2m) to plot

# plot test data
ax.plot(x, np.ones(len(x)), z1)
ax.plot(x, np.ones(len(x))*3, z2)
ax.scatter(x2m, y2m, z2m)    # plot the masked data as points
ax.plot(x, np.ones(len(x))*5, z3)

# make labels
ax.set_xlabel('X')
ax.set_ylabel('Y')
ax.set_zlabel('Z')
ax.set_zlim(0)

# set view angles to get better plot
ax.azim = 220   # z rotation (default=270)
ax.elev = 2     # x rotation (default=0)
ax.dist = 10    # zoom (define perspective)
plt.show()

输出图:

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