How can I use matrix from numpy as the input of some plotting functions in matplotlib?

Question

I want to plot four points (or lines connected to each other) in 3D coordinates. And the coordinates are stored in X, Y and Z. For example, I have the following lines:

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

fig = plt.figure()
ax = fig.gca(projection='3d')
X = np.matrix('-1, 1, 1, 2')
Y = np.matrix('1, 2, 4, 6')
Z = np.matrix('3, 4, 2, 1')

ax.plot(X, Y, Z)
plt.show()

But after running, there will be a type error. I guess it's due to the input of the matrix type in numpy. Anybody know how to easily solve this problem?

Error message:

Traceback (most recent call last):
  File "C:\Users\I077165\Desktop\tmp.py", line 11, in <module>
    ax.plot(X, Y, Z)
  File "C:\Python27\lib\site-packages\mpl_toolkits\mplot3d\axes3d.py", line 1312, in plot
    lines = Axes.plot(self, xs, ys, *args[argsi:], **kwargs)
  File "C:\Python27\lib\site-packages\matplotlib\axes.py", line 3848, in plot
    for line in self._get_lines(*args, **kwargs):
  File "C:\Python27\lib\site-packages\matplotlib\axes.py", line 323, in _grab_next_args
    for seg in self._plot_args(remaining, kwargs):
  File "C:\Python27\lib\site-packages\matplotlib\axes.py", line 284, in _plot_args
    raise ValueError, 'third arg must be a format string'
ValueError: third arg must be a format string

Thanks.

Can you display the actual error ? What's your version of matplotlib ? — Pierre GM
– Pierre GM, Commented Aug 22, 2012 at 8:39
@PierreGM: I just added the error message above. The version of matplotlib is 1.1.0. Thanks — mintaka
– mintaka, Commented Aug 23, 2012 at 4:33

Roland Smith · Accepted Answer · 2012-08-22 08:51:27Z

3

Use np.array() instead of np.matrix() for all three datasets.

So for the X data, np.matrix('-1, 1, 1, 2') should become np.array([-1, 1, 1, 2])

answered Aug 22, 2012 at 8:51

Roland Smith

43.8k3 gold badges69 silver badges98 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

seberg Over a year ago

Note that the arrays must be one dimensional (and matrices are always 2D). So if you want to plot matrices directly, you would have to plot X.A.ravel(), Y.A.ravel() (X.A is just an array view of the matrix).

Collectives™ on Stack Overflow

How can I use matrix from numpy as the input of some plotting functions in matplotlib?

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related