Matplotlib pyplot savefig outputs blank image

Question

I am trying to save plots I make using matplotlib  however  the images are saving blank   Here is my code   plt subplot 121  plt imshow dataStack  cmap mpl cm bone   plt subplot 122  y   copy deepcopy tumorStack  y   np ma masked where y    0  y   plt imshow dataStack  cmap mpl cm bone  plt imshow y  cmap mpl cm jet r  interpolation  nearest    if T0 is not None      plt subplot 123      plt imshow T0  cmap mpl cm bone        plt subplot 124       Autozoom   else       plt subplot 124       Autozoom  plt show   plt draw   plt savefig  tessstttyyy png   dpi 100    And tessstttyyy png is blank  also tried with  jpg

User · Answer

plt show   should come after plt savefig    Explanation  plt show   clears the whole thing  so anything afterwards will happen on a new empty figure

User · Answer

First  what happens when T0 is not None  I would test that  then I would adjust the values I pass to plt subplot    maybe try values 131  132  and 133  or values that depend whether or not T0 exists   Second  after plt show   is called  a new figure is created  To deal with this  you can   Call plt savefig  tessstttyyy png   dpi 100  before you call plt show   Save the figure before you show   by calling plt gcf   for  get current figure   then you can call savefig   on this Figure object at any time    For example    fig1   plt gcf   plt show   plt draw   fig1 savefig  tessstttyyy png   dpi 100    In your code   tesssttyyy png  is blank because it is saving the new figure  to which nothing has been plotted

User · Answer

let s me give a more detail example   import numpy as np import matplotlib pyplot as plt   def draw result lst iter  lst loss  lst acc  title       plt plot lst iter  lst loss   -b   label  loss       plt plot lst iter  lst acc   -r   label  accuracy        plt xlabel  n iteration       plt legend loc  upper left       plt title title      plt savefig title   png      should before plt show method      plt show     def test draw        lst iter   range 100      lst loss    0 01   i   0 01   i    2 for i in xrange 100         lst loss   np random randn 1  100  reshape  100         lst acc    0 01   i - 0 01   i    2 for i in xrange 100         lst acc   np random randn 1  100  reshape  100         draw result lst iter  lst loss  lst acc   sgd method     if   name         main         test draw

User · Answer

Calling savefig before show   worked for me   fig  ax   plt subplots figsize    4 4   sns barplot x  sex   y  tip   color  g   ax ax data tips  sns barplot x  sex   y  tip   color  b   ax ax data tips  ax legend   Male   Female    facecolor  w    plt savefig  figure png   plt show

User · Answer

change the order of the functions fixed the problem for me    first Save the plot then Show the plot   as following   plt savefig  heatmap png    plt show

User · Answer

Call plt show   after plt savefig fig  and your problem should be solved

[python] Matplotlib (pyplot) savefig outputs blank image

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