[Matplotlib-users] How do i store plot data as numpy ndarray..

[vincent.adrien at gmail.com]

Hi,

I think the problem is that you do not actually retrieve the plotted array data 
with `matplotlib.pyplot.get_cmap` but the `matplotlib.colormap.Colormap` 
instance instead (i.e. just the color <-> value mapping).

Please see the following code snippet to achieve something that looks like you 
want if I understood correctly your wish.

```python

import matplotlib.pyplot as plt
import numpy as np

original_data = np.arange(600).reshape((200, -1))
im_opts = {'aspect': 'auto', 'cmap': 'viridis'}

fig, (ax0, ax1) = plt.subplots(ncols=2)

ax0.set_title('From Original Data')
im0 = ax0.imshow(original_data, **im_opts)

# NB: ``get_array`` returns a masked array from `numpy.ma`.  More information:
# https://docs.scipy.org/doc/numpy/reference/maskedarray.generic.html
masked_data = im0.get_array()
np.save('recorded_array.npy', masked_data.data)  # NB: use the mask if needed
reloaded_data = np.load('recorded_array.npy')

ax1.set_title('From Recorded Data')
im1 = ax1.imshow(reloaded_data, **im_opts)

# just to be sure :)
np.testing.assert_allclose(original_data, reloaded_data)

plt.show()

```

Best regards,
Adrien V.

Le 13/05/2017 à 13:52, Carlton Banks a écrit :
> I made this tiny example code for reproducing the output:
> 
> |importnumpy asnp importmatplotlib.pyplot asplt importmatplotlib fromPIL 
> importImageimportlibrosa importlibrosa.display frommatplotlib importcm fig 
> =plt.figure(figsize=(12,4))min =-1.828067max =22.70058data 
> =np.random.uniform(low=min,high=max,size=(474,40))librosa.display.specshow(data.T,sr=16000,x_axis='frames',y_axis='mel',hop_length=160,cmap=cm.jet)plt.show()raw_input("sadas")convert 
> =plt.get_cmap(cm.jet)numpy_output_static 
> =convert(data.T)plt.imshow(numpy_output_static,aspect 
> ='auto')plt.show()raw_input("asds")|
> 
> 
> Which gives two different images, a random plot in first one, and a red plot in 
> the second one.
>> Den 13. maj 2017 kl. 11.50 skrev Carlton Banks <noflaco at gmail.com 
>> <mailto:noflaco at gmail.com>>:
>>
>> Hi guys..
>>
>> I seem to have a problems with converting my plot to a numpy ndarray -
>> Such that if I made a imshow of the numpy ndarray i would see am image similar 
>> to the lmage i created..
>>
>> |librosa.display.specshow(static.T,sr=16000,x_axis='frames',y_axis='mel',hop_length=160,cmap=cm.jet)plt.title("log 
>> mel power spectrum of "+name)plt.colorbar(format='%+02.0f 
>> dB')plt.tight_layout()plt.savefig(plot+"/"+name+"_plot_static_conv.png")plt.show()|
>> This will show an image such as:
>> <JPR6G.png>
>>
>>
>> But if i try to store it as a numpy ndarray and then trying to plot it using 
>> this code
>> |convert =plt.get_cmap(cm.jet)numpy_output_static 
>> =convert(static.T)plt.imshow(numpy_output_static)plt.show()raw_input("sadas")|
>> I see something like this <2WGgJ.png>
> 
> 
> 
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