• 3

A PHP Error was encountered

Severity: Notice

Message: Undefined index: userid

Filename: views/question.php

Line Number: 191


File: /home/prodcxja/public_html/questions/application/views/question.php
Line: 191
Function: _error_handler

File: /home/prodcxja/public_html/questions/application/controllers/Questions.php
Line: 433
Function: view

File: /home/prodcxja/public_html/questions/index.php
Line: 315
Function: require_once

name Punditsdkoslkdosdkoskdo

Matplotlib: “Unknown projection '3d'” error

I just installed matplotlib and am trying to run one of there example scripts. However I run into the error detailed below. What am I doing wrong?

from mpl_toolkits.mplot3d import axes3d
import matplotlib.pyplot as plt

fig = plt.figure()
ax = fig.gca(projection='3d')
X, Y, Z = axes3d.get_test_data(0.05)
cset = ax.contour(X, Y, Z, 16, extend3d=True)
ax.clabel(cset, fontsize=9, inline=1)


The error is

Traceback (most recent call last):
  File "<string>", line 245, in run_nodebug
  File "<module1>", line 5, in <module>
  File "C:\Python26\lib\site-packages\matplotlib\figure.py", line 945, in gca
    return self.add_subplot(111, **kwargs)
  File "C:\Python26\lib\site-packages\matplotlib\figure.py", line 677, in add_subplot
    projection_class = get_projection_class(projection)
  File "C:\Python26\lib\site-packages\matplotlib\projections\__init__.py", line 61, in get_projection_class
    raise ValueError("Unknown projection '%s'" % projection)
ValueError: Unknown projection '3d'

First off, I think mplot3D worked a bit differently in matplotlib version 0.99 than it does in the current version of matplotlib.

Which version are you using? (Try running: python -c 'import matplotlib; print matplotlib."__version__")

I'm guessing you're running version 0.99, in which case you'll need to either use a slightly different syntax or update to a more recent version of matplotlib.

If you're running version 0.99, try doing this instead of using using the projection keyword argument:

import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import axes3d, Axes3D #<-- Note the capitalization! 
fig = plt.figure()

ax = Axes3D(fig) #<-- Note the difference from your original code...

X, Y, Z = axes3d.get_test_data(0.05)
cset = ax.contour(X, Y, Z, 16, extend3d=True)
ax.clabel(cset, fontsize=9, inline=1)

This should work in matplotlib 1.0.x, as well, not just 0.99.

  • 114
Reply Report

Just to add to Joe Kington's answer (not enough reputation for a comment) there is a good example of mixing 2d and 3d plots in the documentation at http://matplotlib.org/examples/mplot3d/mixed_subplots_demo.html which shows projection='3d' working in combination with the Axes3D import.

from mpl_toolkits.mplot3d import Axes3D
ax = fig.add_subplot(2, 1, 1)
ax = fig.add_subplot(2, 1, 2, projection='3d')

In fact as long as the Axes3D import is present the line

from mpl_toolkits.mplot3d import Axes3D
ax = fig.gca(projection='3d')

as used by the OP also works. (checked with matplotlib version 1.3.1)

  • 64
Reply Report
      • 2
    • The import statement made it work for me. But I can't help feel icky by running this code... Using a import statement to bootstrap some code that looks totally separated on the surface seems like a bad design
    • ax = fig.gca(projection='3d') does work for me. Instead of ax = plt.subplot(111,projection="3d"). I'm using the version of 2.1.0
    • @Ezbob the whole matplotlib API is just a pain in the ass. I always have to google if I want to create even a basic plot. No other python lib has such a crappy API
    • This is actually really helpful to know! While the Axes3D import is never explicitly used it enables projection='3d' to be used without error

I encounter the same problem, and @Joe Kington and @bvanlew's answer solve my problem.

but I should add more infomation when you use pycharm and enable auto import.

when you format the code, the code from mpl_toolkits.mplot3d import Axes3D will auto remove by pycharm.

so, my solution is

from mpl_toolkits.mplot3d import Axes3D
Axes3D = Axes3D  # pycharm auto import
fig = plt.figure()
ax = fig.add_subplot(111, projection='3d')

and it works well!

  • 4
Reply Report

Try this:

import matplotlib.pyplot as plt
import seaborn as sns
from mpl_toolkits.mplot3d import axes3d


  • 0
Reply Report

Trending Tags