AttributeError while adding colorbar in matplotlib

Question

The following code fails to run on Python 2.5.4: ``` from matplotlib import pylab as pl import numpy as np data = np.random.rand(6,6) fig = pl.figure(1) fig.clf() ax = fig.add_subplot(1,1,1) ax.imshow(data, interpolation='nearest', vmin=0.5, vmax=0.99) pl.colorbar() pl.show() ``` The error message is ``` C:	emp>python z.py Traceback (most recent call last): File "z.py", line 10, in <module> pl.colorbar() File "C:\Python25\lib\site-packages\matplotlib\pyplot.py", line 1369, in colorbar ret = gcf().colorbar(mappable, cax = cax, ax=ax, **kw) File "C:\Python25\lib\site-packages\matplotlib\figure.py", line 1046, in colorbar cb = cbar.Colorbar(cax, mappable, **kw) File "C:\Python25\lib\site-packages\matplotlib\colorbar.py", line 622, in __init__ mappable.autoscale_None() # Ensure mappable.norm.vmin, vmax AttributeError: 'NoneType' object has no attribute 'autoscale_None' ``` How can I add colorbar to this code? Following is the interpreter information: ``` Python 2.5.4 (r254:67916, Dec 23…

Accepted Answer

Note: I am using python 2.6.2. The same error was raised with your code and the following modification solved the problem.

I read the following colorbar example: http://matplotlib.sourceforge.net/examples/pylab_examples/colorbar_tick_labelling_demo.html

```
from matplotlib import pylab as pl
import numpy as np

data = np.random.rand(6,6)
fig = pl.figure(1)
fig.clf()
ax = fig.add_subplot(1,1,1)
img = ax.imshow(data, interpolation='nearest', vmin=0.5, vmax=0.99)
fig.colorbar(img)

pl.show()
```

Not sure why your example didn't work. I'm not that familiar with matplotlib.

AttributeError while adding colorbar in matplotlib

Solution

Problem