python subplot for loop

Question

I'm trying to use a for lop to populate a subplot but I can't do so. here is a summary of my code: Edit 1:

for idx in range(8):
  img = f[img_set[ind[idx]][0]]
  patch = img[:,col1+1:col2, row1+1:row2]
  if idx < 3:
        axarr[0,idx] = plt.imshow(patch)
    elif idx <6:
        axarr[1,idx-3] = plt.imshow(patch)
    else:
        axarr[2,idx-6] = plt.imshow(patch)
path_ = 'plots/test' + str(k) + '.pdf'
fig.savefig(path_)

It only plots an image on the 3rd row and 3rd column the rest of the plot is blank. How can I change that?

I cut out chunk of the code to get to my problem. I'm loading an image set and i'm only interested in parts of an image I pre_defined(row1,row2,col1,col2) and want to plot these different images on a subplot. — user1871528
– user1871528, Commented Jun 6, 2016 at 20:20

Julien Spronck · Accepted Answer · 2016-06-06 20:36:07Z

2

You forgot to create the sub plots. You can use add_subplot() (http://matplotlib.org/api/figure_api.html#matplotlib.figure.Figure.add_subplot). For example,

import matplotlib.pyplot as plt

fig = plt.figure()

for idx in xrange(9):
    ax = fig.add_subplot(3, 3, idx+1) # this line adds sub-axes
    ...
    ax.imshow(patch) # this line creates the image using the pre-defined sub axes

fig.savefig('test.png')

In your example, it could be something like:

import matplotlib.pyplot as plt

fig = plt.figure()

for idx in xrange(8):
    ax = fig.add_subplot(3, 3, idx+1)
    img = f[img_set[ind[idx]][0]]
    patch = img[:,col1+1:col2, row1+1:row2]
    ax.imshow(patch)

path_ = 'plots/test' + str(k) + '.pdf'        
fig.savefig(path_)

edited Jun 6, 2016 at 20:36

answered Jun 6, 2016 at 20:28

Julien Spronck

15.5k5 gold badges50 silver badges57 bronze badges

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

1 Comment

user1871528 Over a year ago

I forgot to copy and paste where i created the subplot. but your solution of fig.add_subplot did the trick Thanks.

Collectives™ on Stack Overflow

python subplot for loop

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