Save plot to image file instead of displaying it using Matplotlib

Question

I am writing a quick-and-dirty script to generate plots on the fly  I am using the code below  from Matplotlib documentation  as a starting point   from pylab import figure  axes  pie  title  show    Make a square figure and axes figure 1  figsize  6  6   ax   axes  0 1  0 1  0 8  0 8    labels    Frogs    Hogs    Dogs    Logs  fracs    15  30  45  10   explode    0  0 05  0  0  pie fracs  explode explode  labels labels  autopct   1 1f     shadow True  title  Raining Hogs and Dogs   bbox   facecolor    0 8    pad   5    show      Actually  don t show  just save to foo png   I don t want to display the plot on a GUI  instead  I want to save the plot to a file  say foo png   so that  for example  it can be used in batch scripts  How do I do that

User · Answer

Just found this link on the MatPlotLib documentation addressing exactly this issue: http://matplotlib.org/faq/howto_faq.html#generate-images-without-having-a-window-appear

They say that the easiest way to prevent the figure from popping up is to use a non-interactive backend (eg. Agg), via matplotib.use(<backend>), eg:

import matplotlib
matplotlib.use('Agg')
import matplotlib.pyplot as plt
plt.plot([1,2,3])
plt.savefig('myfig')

I still personally prefer using plt.close( fig ), since then you have the option to hide certain figures (during a loop), but still display figures for post-loop data processing. It is probably slower than choosing a non-interactive backend though - would be interesting if someone tested that.

UPDATE: for Spyder, you usually can't set the backend in this way (Because Spyder usually loads matplotlib early, preventing you from using matplotlib.use()).

Instead, use plt.switch_backend('Agg'), or Turn off "enable support" in the Spyder prefs and run the matplotlib.use('Agg') command yourself.

From these two hints: one, two

User · Answer

As others have said  plt savefig   or fig1 savefig   is indeed the way to save an image   However I ve found that in certain cases the figure is always shown   eg  with Spyder having plt ion    interactive mode   On    I work around this by forcing the closing of the figure window in my giant loop with plt close figure object   see documentation   so I don t have a million open figures during the loop   import matplotlib pyplot as plt fig  ax   plt subplots  nrows 1  ncols 1      create figure  amp  1 axis ax plot  0 1 2    10 20 3   fig savefig  path to save image to png       save the figure to file plt close fig       close the figure window   You should be able to re-open the figure later if needed to with fig show    didn t test myself

User · Answer

While the question has been answered  I d like to add some useful tips when using matplotlib pyplot savefig  The file format can be specified by the extension  from matplotlib import pyplot as plt  plt savefig  foo png   plt savefig  foo pdf    Will give a rasterized or vectorized output respectively  both which could be useful  In addition  you ll find that pylab leaves a generous  often undesirable  whitespace around the image  You can remove the whitespace using  plt savefig  foo png   bbox inches  tight

User · Answer

I used the following   import matplotlib pyplot as plt  p1   plt plot dates  temp   r-   label  Temperature  celsius      p2   plt plot dates  psal   b-   label  Salinity  psu      plt legend loc  upper center   numpoints 1  bbox to anchor  0 5  -0 05          ncol 2  fancybox True  shadow True   plt savefig  data png     plt show     f close   plt close     I found very important to use plt show after saving the figure  otherwise it won t work figure exported in png

User · Answer

As suggested before  you can either use   import matplotlib pyplot as plt plt savefig  myfig png     For saving whatever IPhython image that you are displaying  Or on a different note  looking from a different angle   if you ever get to work with open cv  or if you have open cv imported  you can go for   import cv2  cv2 imwrite  myfig png  image   But this is just in case if you need to work with Open CV  Otherwise plt savefig   should be sufficient

User · Answer

If  like me  you use Spyder IDE  you have to disable the interactive mode with    plt ioff     this command is automatically launched with the scientific startup   If you want to enable it again  use    plt ion

User · Answer

You can either do    plt show hold False  plt savefig  name pdf     and remember to let savefig finish before closing the GUI plot  This way you can see the image beforehand    Alternatively  you can look at it with plt show   Then close the GUI and run the script again  but this time replace plt show   with plt savefig      Alternatively  you can use   fig  ax   plt figure nrows 1  ncols 1  plt plot      plt show   fig savefig  out pdf

User · Answer

You can do it like this   def plotAFig      plt figure     plt plot x y  b-     plt savefig  figurename png     plt close

User · Answer

When using matplotlib pyplot  you must first save your plot and then close it using these 2 lines   fig savefig  plot png     save the plot  place the path you want to save the figure in quotation plt close fig    close the figure window

User · Answer

After using the plot   and other functions to create the content you want  you could use a clause like this to select between plotting to the screen or to file   import matplotlib pyplot as plt  fig   plt figure figsize  4  5           size in inches   use plot    etc  to create your plot     Pick one of the following lines to uncomment   save file   None   save file   os path join your directory  your file name     if save file      plt savefig save file      plt close fig  else      plt show

User · Answer

Given that today  was not available when this question was made  lots of people use Jupyter Notebook as python console  there is an extremely easy way to save the plots as  png  just call the matplotlib s pylab class from Jupyter Notebook  plot the figure  inline  jupyter cells  and then drag that figure image to a local directory  Don t forget   matplotlib inline in the first line

User · Answer

import datetime import numpy as np from matplotlib backends backend pdf import PdfPages import matplotlib pyplot as plt    Create the PdfPages object to which we will save the pages    The with statement makes sure that the PdfPages object is closed properly at   the end of the block  even if an Exception occurs  with PdfPages  multipage pdf pdf   as pdf      plt figure figsize  3  3       plt plot range 7    3  1  4  1  5  9  2    r-o       plt title  Page One       pdf savefig      saves the current figure into a pdf page     plt close        plt rc  text   usetex True      plt figure figsize  8  6       x   np arange 0  5  0 1      plt plot x  np sin x    b-       plt title  Page Two       pdf savefig       plt close        plt rc  text   usetex False      fig   plt figure figsize  4  5       plt plot x  x x   ko       plt title  Page Three       pdf savefig fig     or you can pass a Figure object to pdf savefig     plt close          We can also set the file s metadata via the PdfPages object      d   pdf infodict       d  Title      Multipage PDF Example      d  Author     u Jouni K  Sepp xe4nen      d  Subject      How to create a multipage pdf file and set its metadata      d  Keywords      PdfPages multipage keywords author title subject      d  CreationDate     datetime datetime 2009  11  13      d  ModDate     datetime datetime today

User · Answer

You can save your image with any extension png  jpg etc   and with the resolution you want  Here s a function to save your figure    import os  def save fig fig id  tight layout True  fig extension  png   resolution 300       path   os path join IMAGES PATH  fig id         fig extension      print  Saving figure   fig id      if tight layout          plt tight layout       plt savefig path  format fig extension  dpi resolution     fig id  is the name by which you want to save your figure  Hope it helps

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The Solution     import pandas as pd import numpy as np import matplotlib pyplot as plt import matplotlib matplotlib style use  ggplot   ts   pd Series np random randn 1000   index pd date range  1 1 2000   periods 1000   ts   ts cumsum   plt figure   ts plot   plt savefig  foo png   bbox inches  tight     If you do want to display the image as well as saving the image use    matplotlib inline   after  import matplotlib

User · Answer

According to question Matplotlib  pyplot  savefig outputs blank image   One thing should note  if you use plt show and it should after plt savefig  or you will give a blank image   A detailed 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

The solution is    pylab savefig  foo png

User · Answer

The other answers are correct   However  I sometimes find that I want to open the figure object later   For example  I might want to change the label sizes  add a grid  or do other processing   In a perfect world  I would simply rerun the code generating the plot  and adapt the settings   Alas  the world is not perfect   Therefore  in addition to saving to PDF or PNG  I add   with open  some file pkl    wb   as fp      pickle dump fig  fp  protocol 4    Like this  I can later load the figure object and manipulate the settings as I please   I also write out the stack with the source-code and locals   dictionary for each function method in the stack  so that I can later tell exactly what generated the figure   NB  Be careful  as sometimes this method generates huge files

User · Answer

import matplotlib pyplot as plt plt savefig  image png     In Jupyter Notebook you have to remove plt show   and add plt savefig    together with the rest of the plt-code in one cell  The image will still show up in your notebook

User · Answer

If you don t like the concept of the  current  figure  do   import matplotlib image as mpimg  img   mpimg imread  src png   mpimg imsave  out png   img

User · Answer

Additionally to those above  I added   file   for the name so the picture and Python file get the same names  I also added few arguments to make It look better     Saves a PNG file of the current graph to the folder and updates it every time    nameOfimage  dpi  sizeOfimage  Keeps Labels From Disappearing  plt savefig   file     png  dpi  250   bbox inches  tight     Hard coded name     test png

[python] Save plot to image file instead of displaying it using Matplotlib

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