使用plt.quiver绘图时遭遇ufunc 'isfinite' TypeError问题求助

问题代码 #

import matplotlib.pyplot as plt

x=[0.5, 0.09113826200606436, 0.09090926587458355, 0.09090909053329622, 0.09090909090689524, 0.09090909090901886]
y=[-0.5, -0.09113826200606436, -0.09090926587458355, -0.09090909053329618, -0.09090909090689503, -0.09090909090901889]
u=[0.9, 0.0005041764133415783, 3.84924083801641e-07, -8.267483364576833e-10, -4.830719158022134e-12, -1.584843367652411e-13]
v=[-0.9, -0.0005041764133415783, -3.84924083801641e-07, 8.267483364576833e-10, 4.830691402446519e-12, 1.584843367652411e-13]
colour=['red', 'red', 'red', 'red', 'red', 'red']

plt.quiver(x,y,u,v, colour)

报错信息 #

TypeError    Traceback (most recent call last)
<ipython-input-12-2e445afc7e85> in <module>
    138 print(colour)
    139 plt.rcParams["figure.figsize"] = (30,30)
--> 140 plt.quiver(x,y,u,v, colour)
    141 plt.scatter(stable_point_xaxis, stable_point_yaxis, color='blue')
    142 #plt.scatter(uNew, vNew, color='red')

5 frames
/usr/local/lib/python3.7/dist-packages/numpy/ma/core.py in masked_invalid(a, copy)
   2367         cls = type(a)
   2368     else:
-> 2369         condition = ~(np.isfinite(a))
   2370         cls = MaskedArray
   2371     result = a.view(cls)

TypeError: ufunc 'isfinite' not supported for the input types, and the inputs could not be safely coerced to any supported types according to the casting rule ''safe''

问题原因 #

plt.quiver函数的参数顺序中，前四个参数是x, y, u, v，第五个位置参数是scale（用于缩放矢量的数值参数），而非颜色。直接传入字符串列表colour会导致numpy尝试对字符串执行np.isfinite（检查数值是否有限）操作，而字符串不支持该函数，因此抛出类型错误。

解决方案 #

需要通过**关键字参数color**来指定矢量颜色，而非位置参数传递。

修改后的代码（方式一：指定颜色列表） #

import matplotlib.pyplot as plt

x=[0.5, 0.09113826200606436, 0.09090926587458355, 0.09090909053329622, 0.09090909090689524, 0.09090909090901886]
y=[-0.5, -0.09113826200606436, -0.09090926587458355, -0.09090909053329618, -0.09090909090689503, -0.09090909090901889]
u=[0.9, 0.0005041764133415783, 3.84924083801641e-07, -8.267483364576833e-10, -4.830719158022134e-12, -1.584843367652411e-13]
v=[-0.9, -0.0005041764133415783, -3.84924083801641e-07, 8.267483364576833e-10, 4.830691402446519e-12, 1.584843367652411e-13]
colour=['red', 'red', 'red', 'red', 'red', 'red']

plt.rcParams["figure.figsize"] = (30,30)
plt.quiver(x, y, u, v, color=colour)
plt.show()

简化方式（所有矢量颜色一致） #

因为所有矢量颜色都是红色，可直接传入单个颜色字符串，无需列表：

plt.quiver(x, y, u, v, color='red')

内容的提问来源于stack exchange，提问作者CSProgrammer