Python: subplot within a loop: first panel appears in wrong position

Question

I am fairly new to Python and come from a more Matlab point of view.
I am trying to make a series of 2 x 5 panel contourf subplots. My approach so far
has been to convert (to a certain degree) my Matlab code to Python and plot my subplots within a loop. The relavent part of the code looks like this:

fig=plt.figure(figsize=(15, 6),facecolor='w', edgecolor='k')
for i in range(10):

    #this part is just arranging the data for contourf 
    ind2 = py.find(zz==i+1)
    sfr_mass_mat = np.reshape(sfr_mass[ind2],(pixmax_x,pixmax_y))
    sfr_mass_sub = sfr_mass[ind2]
    zi = griddata(massloclist, sfrloclist, sfr_mass_sub,xi,yi,interp='nn')


    temp = 250+i  # this is to index the position of the subplot
    ax=plt.subplot(temp)
    ax.contourf(xi,yi,zi,5,cmap=plt.cm.Oranges)
    plt.subplots_adjust(hspace = .5,wspace=.001)

    #just annotating where each contour plot is being placed
    ax.set_title(str(temp))

As a newbie to this forum, i dont seem to be allowed to attach the resulting image. However, going by my indexing in the code as ‘temp’ the resulting layout of the the 2 x 5 panels is:

251 - 252 - 253 - 254 - 255
256 - 257 - 258 - 259 - 250

However, what i want is

250 - 251 - 252 - 253 - 254
255 - 256 - 257 - 258 - 259

That is, the first panel (250) appears in the last position where i would think 259 should be. And 251 seems to be where i want 250 to be placed. They all seem to be in the correct sequence, just circularly shifted by one.

I know this will be something very silly, but appreciate any help you can give.

Thank you in advance.

Asked By: russell johnston

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Source

Answer 1

Using your code with some random data, this would work:

fig, axs = plt.subplots(2,5, figsize=(15, 6), facecolor='w', edgecolor='k')
fig.subplots_adjust(hspace = .5, wspace=.001)

axs = axs.ravel()

for i in range(10):

    axs[i].contourf(np.random.rand(10,10),5,cmap=plt.cm.Oranges)
    axs[i].set_title(str(250+i))

The layout is off course a bit messy, but that’s because of your current settings (the figsize, wspace etc).

enter image description here

Answered By: Rutger Kassies

Answer 2

The problem is the indexing subplot is using. Subplots are counted starting with 1!
Your code thus needs to read

fig=plt.figure(figsize=(15, 6),facecolor='w', edgecolor='k')
for i in range(10):

    #this part is just arranging the data for contourf 
    ind2 = py.find(zz==i+1)
    sfr_mass_mat = np.reshape(sfr_mass[ind2],(pixmax_x,pixmax_y))
    sfr_mass_sub = sfr_mass[ind2]
    zi = griddata(massloclist, sfrloclist, sfr_mass_sub,xi,yi,interp='nn')


    temp = 251+i  # this is to index the position of the subplot
    ax=plt.subplot(temp)
    ax.contourf(xi,yi,zi,5,cmap=plt.cm.Oranges)
    plt.subplots_adjust(hspace = .5,wspace=.001)

    #just annotating where each contour plot is being placed
    ax.set_title(str(temp))

Note the change in the line where you calculate temp

Answered By: David Zwicker

Answer 3

Basically the same solution as provided by Rutger Kassies, but using a more pythonic syntax:

fig, axs = plt.subplots(2,5, figsize=(15, 6), facecolor='w', edgecolor='k')
fig.subplots_adjust(hspace = .5, wspace=.001)

data = np.arange(250, 260)

for ax, d in zip(axs.ravel(), data):
    ax.contourf(np.random.rand(10,10), 5, cmap=plt.cm.Oranges)
    ax.set_title(str(d))

Answered By: Tim Hoffmann

Python: subplot within a loop: first panel appears in wrong position

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