[python] How to make pylab.savefig() save image for 'maximized' window instead of default size

I am using pylab in matplotlib to create a plot and save the plot to an image file. However, when I save the image using pylab.savefig( image_name ), I find that the SIZE image saved is the same as the image that is shown when I use pylab.show().

As it happens, I have a lot of data in the plot and when I am using pylab.show(), I have to maximize the window before I can see all of the plot correctly, and the xlabel tickers don't superimpose on each other.

Is there anyway that I can programmatically 'maximize' the window before saving the image to file? - at the moment, I am only getting the 'default' window size image, which results in the x axis labels being superimposed on one another.

I did the same search time ago, it seems that he exact solution depends on the backend.

I have read a bunch of sources and probably the most useful was the answer by Pythonio here How to maximize a plt.show() window using Python I adjusted the code and ended up with the function below. It works decently for me on windows, I mostly use Qt, where I use it quite often, while it is minimally tested with other backends.

Basically it consists in identifying the backend and calling the appropriate function. Note that I added a pause afterwards because I was having issues with some windows getting maximized and others not, it seems this solved for me.

def maximize(backend=None,fullscreen=False):
    """Maximize window independently on backend.
    Fullscreen sets fullscreen mode, that is same as maximized, but it doesn't have title bar (press key F to toggle full screen mode)."""
    if backend is None:
        backend=matplotlib.get_backend()
    mng = plt.get_current_fig_manager()

    if fullscreen:
        mng.full_screen_toggle()
    else:
        if backend == 'wxAgg':
            mng.frame.Maximize(True)
        elif backend == 'Qt4Agg' or backend == 'Qt5Agg':
            mng.window.showMaximized()
        elif backend == 'TkAgg':
            mng.window.state('zoomed') #works fine on Windows!
        else:
            print ("Unrecognized backend: ",backend) #not tested on different backends (only Qt)
    plt.show()

    plt.pause(0.1) #this is needed to make sure following processing gets applied (e.g. tight_layout)

I think you need to specify a different resolution when saving the figure to a file:

fig = matplotlib.pyplot.figure()
# generate your plot
fig.savefig("myfig.png",dpi=600)

Specifying a large dpi value should have a similar effect as maximizing the GUI window.

Check this: How to maximize a plt.show() window using Python

The command is different depending on which backend you use. I find that this is the best way to make sure the saved pictures have the same scaling as what I view on my screen.

Since I use Canopy with the QT backend:

pylab.get_current_fig_manager().window.showMaximized()

I then call savefig() as required with an increased DPI per silvado's answer.

I had this exact problem and this worked:

plt.savefig(output_dir + '/xyz.png', bbox_inches='tight')

Here is the documentation:

[https://matplotlib.org/3.1.1/api/_as_gen/matplotlib.pyplot.savefig.html][1]

You can look in a saved figure it's size, like 1920x983 px (size when i saved a maximized window), then I set the dpi as 100 and the size as 19.20x9.83 and it worked fine. Saved exactly equal to the maximized figure.

import numpy as np
import matplotlib.pyplot as plt
x, y = np.genfromtxt('fname.dat', usecols=(0,1), unpack=True)
a = plt.figure(figsize=(19.20,9.83))
a = plt.plot(x, y, '-')
plt.savefig('file.png',format='png',dpi=100)

There are two major options in matplotlib (pylab) to control the image size:

1. You can set the size of the resulting image in inches
2. You can define the DPI (dots per inch) for output file (basically, it is a resolution)

Normally, you would like to do both, because this way you will have full control over the resulting image size in pixels. For example, if you want to render exactly 800x600 image, you can use DPI=100, and set the size as 8 x 6 in inches:

import matplotlib.pyplot as plt
# plot whatever you need...
# now, before saving to file:
figure = plt.gcf() # get current figure
figure.set_size_inches(8, 6)
# when saving, specify the DPI
plt.savefig("myplot.png", dpi = 100)

One can use any DPI. In fact, you might want to play with various DPI and size values to get the result you like the most. Beware, however, that using very small DPI is not a good idea, because matplotlib may not find a good font to render legend and other text. For example, you cannot set the DPI=1, because there are no fonts with characters rendered with 1 pixel :)

From other comments I understood that other issue you have is proper text rendering. For this, you can also change the font size. For example, you may use 6 pixels per character, instead of 12 pixels per character used by default (effectively, making all text twice smaller).

import matplotlib
#...
matplotlib.rc('font', size=6)

Finally, some references to the original documentation: http://matplotlib.sourceforge.net/api/pyplot_api.html#matplotlib.pyplot.savefig, http://matplotlib.sourceforge.net/api/pyplot_api.html#matplotlib.pyplot.gcf, http://matplotlib.sourceforge.net/api/figure_api.html#matplotlib.figure.Figure.set_size_inches, http://matplotlib.sourceforge.net/users/customizing.html#dynamic-rc-settings

P.S. Sorry, I didn't use pylab, but as far as I'm aware, all the code above will work same way in pylab - just replace plt in my code with the pylab (or whatever name you assigned when importing pylab). Same for matplotlib - use pylab instead.

If I understand correctly what you want to do, you can create your figure and set the size of the window. Afterwards, you can save your graph with the matplotlib toolbox button. Here an example:

from pylab import get_current_fig_manager,show,plt,imshow

plt.Figure()
thismanager = get_current_fig_manager()
thismanager.window.wm_geometry("500x500+0+0") 
#in this case 500 is the size (in pixel) of the figure window. In your case you want to maximise to the size of your screen or whatever

imshow(your_data)
show()