ChatGPT解决这个技术问题 Extra ChatGPT

How do I change the size of figures drawn with Matplotlib?

How do I change the size of figure drawn with Matplotlib?


L
Luis Mendo

figure tells you the call signature:

from matplotlib.pyplot import figure

figure(figsize=(8, 6), dpi=80)

figure(figsize=(1,1)) would create an inch-by-inch image, which would be 80-by-80 pixels unless you also give a different dpi argument.


If you've already got the figure created, say it's 'figure 1' (that's the default one when you're using pyplot), you can use figure(num=1, figsize=(8, 6), ...) to change it's size etc. If you're using pyplot/pylab and show() to create a popup window, you need to call figure(num=1,...) before you plot anything - pyplot/pylab creates a figure as soon as you draw something, and the size of the popup appears to be fixed at this point.
Does this mean if you set DPI to 1, then figsize becomes a pixel unit instead of an inch unit? This would be more useful when using matplotlib on web and GUI interfaces.
with figsize(1,1) you will have a ratio in the image as 1:1? because all my pie charts are show oval, and the only way I found to make them round was by using plot.axis("equals"). they would have the same effect or they behave diferently?
@BrenoBaiardi This question is about the figure size. The axes on top of the figure may still have an unequal aspect ratio even if the figure as a whole is 1:1, and even if the axes box is 1:1, the data may be scaled differently in the x and y directions. So, no, that command will not guarantee an equal aspect ratio.
Note that if you set a too large number in figsize, the figure will only maximize to until the edges of the screen. This opens the possibility for a horizontal maximization and a vertical maximization.
H
Henry Ecker

If you've already got the figure created, you can use figure.set_size_inches to adjust the figure size:

fig = matplotlib.pyplot.gcf()
fig.set_size_inches(18.5, 10.5)
fig.savefig('test2png.png', dpi=100)

To propagate the size change to an existing GUI window, add forward=True:

fig.set_size_inches(18.5, 10.5, forward=True)

Additionally as Erik Shilts mentioned in the comments you can also use figure.set_dpi to "[s]et the resolution of the figure in dots-per-inch"

fig.set_dpi(100)

Solved me a problem with imshow, now I'm using this code just after eliminating the space around the plotting area with plt.subplots_adjust(left=0.0, right=1.0, bottom=0.0, top=1.0).
Similarly, you can run fig.set_dpi(100).
I'm using this on OS X under ipython 3.7, matplotlib 3.0.3. I am able to adjust the figure size, but the window does not resize (the figure canvas adjusts, but the window does not grow or shrink to accommodate the canvas). The forward=True keyword argument does not appear to have the intended effect on this platform.
Window resize wasn't working for me. It looked like forward=True was key, but it didn't fix it. Turns out it did fix it, I just to be careful about the order that set_size_inches was called. It needed to be called after the call to tight_layout(). I had this issue with an axes.bar plot, I didn't have it with regular plots.
should be called before .show()
E
Eiron

Using plt.rcParams

There is also this workaround in case you want to change the size without using the figure environment. So in case you are using plt.plot() for example, you can set a tuple with width and height.

import matplotlib.pyplot as plt
plt.rcParams["figure.figsize"] = (20,3)

This is very useful when you plot inline (e.g., with IPython Notebook). As asmaier noticed, it is preferable to not put this statement in the same cell of the imports statements.

To reset the global figure size back to default for subsequent plots:

plt.rcParams["figure.figsize"] = plt.rcParamsDefault["figure.figsize"]

Conversion to cm

The figsize tuple accepts inches, so if you want to set it in centimetres you have to divide them by 2.54. Have a look at this question.


Excellent! Also useful for setting it once and plotting multiple times.
For some reason, it seems to this no longer works in Jupyter notebook (but used to).
@Ray Can you write the version of your Jupyter notebook and the behaviour for me it works
To make it work I need to call plt.rcParams["figure.figsize"] = (20,3) in an extra cell. When I call it in the same cell as the import statement, it gets ignored.
To reset the global figure size for subsequent plots back to default use plt.rcParams['figure.figsize'] = plt.rcParamsDefault['figure.figsize']
P
Peter Duniho

Deprecation note: As per the official Matplotlib guide, usage of the pylab module is no longer recommended. Please consider using the matplotlib.pyplot module instead, as described by this other answer.

The following seems to work:

from pylab import rcParams
rcParams['figure.figsize'] = 5, 10

This makes the figure's width 5 inches, and its height 10 inches.

The Figure class then uses this as the default value for one of its arguments.


This also works nicely at the top of a iPython notebook, which (given --pylab=inline) has rcParams already imported at the top level.
This did not work on my Windows machine with OO interface to pyplot and Qt backend. fig.set_size_inches(18.5, 10.5, forward=True) worked.
This answer is currently discussed on Meta
For Python version: 3.6.4, matplotlib: 2.2.3 I think you need to pass a list or tuple e.g. rcParams['figure.figsize'] = (5, 10)
Anyone knows why this does not work at the first time running the cell?
c
cbare

Please try a simple code as following:

from matplotlib import pyplot as plt
plt.figure(figsize=(1,1))
x = [1,2,3]
plt.plot(x, x)
plt.show()

You need to set the figure size before you plot.


This answer tells me that that it is matplotlib.pyplot.figure, which the others do not say as clearly. I keep trying things like matplotlib.figure and matplotlib.figure.Figure
"_tkinter.TclError: not enough free memory for image buffer"
plt.figure(figsize=(1,1)) is the crux move. Thank you.
In jupyter notebook, this worked for me : plt.figure(figsize=(20,10))
For those using jupyter notebook, please make sure you are using plt.figure(figsize=(15, 10)) before other plt commands.
K
Kris

In case you're looking for a way to change the figure size in Pandas, you could do:

df['some_column'].plot(figsize=(10, 5))

where df is a Pandas dataframe. Or, to use an existing figure or axes:

fig, ax = plt.subplots(figsize=(10, 5))
df['some_column'].plot(ax=ax)

If you want to change the default settings, you could do the following:

import matplotlib

matplotlib.rc('figure', figsize=(10, 5))

For more details, check out the docs: pd.DataFrame.plot.


a
amalik2205
import matplotlib.pyplot as plt
plt.figure(figsize=(20,10))
plt.plot(x,y) ## This is your plot
plt.show()

You can also use:

fig, ax = plt.subplots(figsize=(20, 10))

C
Community

The first link in Google for 'matplotlib figure size' is AdjustingImageSize (Google cache of the page).

Here's a test script from the above page. It creates test[1-3].png files of different sizes of the same image:

#!/usr/bin/env python
"""
This is a small demo file that helps teach how to adjust figure sizes
for matplotlib

"""

import matplotlib
print "using MPL version:", matplotlib.__version__
matplotlib.use("WXAgg") # do this before pylab so you don'tget the default back end.

import pylab
import numpy as np

# Generate and plot some simple data:
x = np.arange(0, 2*np.pi, 0.1)
y = np.sin(x)

pylab.plot(x,y)
F = pylab.gcf()

# Now check everything with the defaults:
DPI = F.get_dpi()
print "DPI:", DPI
DefaultSize = F.get_size_inches()
print "Default size in Inches", DefaultSize
print "Which should result in a %i x %i Image"%(DPI*DefaultSize[0], DPI*DefaultSize[1])
# the default is 100dpi for savefig:
F.savefig("test1.png")
# this gives me a 797 x 566 pixel image, which is about 100 DPI

# Now make the image twice as big, while keeping the fonts and all the
# same size
F.set_size_inches( (DefaultSize[0]*2, DefaultSize[1]*2) )
Size = F.get_size_inches()
print "Size in Inches", Size
F.savefig("test2.png")
# this results in a 1595x1132 image

# Now make the image twice as big, making all the fonts and lines
# bigger too.

F.set_size_inches( DefaultSize )# resetthe size
Size = F.get_size_inches()
print "Size in Inches", Size
F.savefig("test3.png", dpi = (200)) # change the dpi
# this also results in a 1595x1132 image, but the fonts are larger.

Output:

using MPL version: 0.98.1
DPI: 80
Default size in Inches [ 8.  6.]
Which should result in a 640 x 480 Image
Size in Inches [ 16.  12.]
Size in Inches [ 16.  12.]

Two notes:

The module comments and the actual output differ. This answer allows easily to combine all three images in one image file to see the difference in sizes.


Every time I am trying to recall how to do it I end up in this post. So, this is the code i am normally looking for: fig = plt.figure() default_size = fig.get_size_inches() fig.set_size_inches( (default_size[0]*2, default_size[1]*2) )
R
River

You can simply use (from matplotlib.figure.Figure):

fig.set_size_inches(width,height)

As of Matplotlib 2.0.0, changes to your canvas will be visible immediately, as the forward keyword defaults to True.

If you want to just change the width or height instead of both, you can use

fig.set_figwidth(val) or fig.set_figheight(val)

These will also immediately update your canvas, but only in Matplotlib 2.2.0 and newer.

For Older Versions

You need to specify forward=True explicitly in order to live-update your canvas in versions older than what is specified above. Note that the set_figwidth and set_figheight functions don’t support the forward parameter in versions older than Matplotlib 1.5.0.


R
Renaud

Try commenting out the fig = ... line

%matplotlib inline
import numpy as np
import matplotlib.pyplot as plt

N = 50
x = np.random.rand(N)
y = np.random.rand(N)
area = np.pi * (15 * np.random.rand(N))**2

fig = plt.figure(figsize=(18, 18))
plt.scatter(x, y, s=area, alpha=0.5)
plt.show()

P
Peter Mortensen

This works well for me:

from matplotlib import pyplot as plt

F = plt.gcf()
Size = F.get_size_inches()
F.set_size_inches(Size[0]*2, Size[1]*2, forward=True) # Set forward to True to resize window along with plot in figure.
plt.show() # Or plt.imshow(z_array) if using an animation, where z_array is a matrix or NumPy array

This forum post might also help: Resizing figure windows


Window resize wasn't working for me. It looked like forward=True was key, but it didn't fix it. Turns out it did fix it, I just to be careful about the order that set_size_inches was called. It needed to be called after the call to tight_layout(). I had this issue with an axes.bar plot, I didn't have it with regular plots.
C
Ciro Santilli Путлер Капут 六四事

Comparison of different approaches to set exact image sizes in pixels

This answer will focus on:

savefig: how to save to a file, not just show on screen

setting the size in pixels

Here is a quick comparison of some of the approaches I've tried with images showing what the give.

Summary of current status: things are messy, not sure if it is a fundamental limitation, or if the use case just didn't get enough attention from devs, I couldn't easily find an upstream discussion about this.

Baseline example without trying to set the image dimensions

Just to have a comparison point:

base.py

#!/usr/bin/env python3

import sys

import numpy as np
import matplotlib.pyplot as plt
import matplotlib as mpl

fig, ax = plt.subplots()
print('fig.dpi = {}'.format(fig.dpi))
print('fig.get_size_inches() = ' + str(fig.get_size_inches())
t = np.arange(-10., 10., 1.)
plt.plot(t, t, '.')
plt.plot(t, t**2, '.')
ax.text(0., 60., 'Hello', fontdict=dict(size=25))
plt.savefig('base.png', format='png')

run:

./base.py
identify base.png

outputs:

fig.dpi = 100.0
fig.get_size_inches() = [6.4 4.8]
base.png PNG 640x480 640x480+0+0 8-bit sRGB 13064B 0.000u 0:00.000

https://i.stack.imgur.com/jtD8D.png

My best approach so far: plt.savefig(dpi=h/fig.get_size_inches()[1] height-only control

I think this is what I'll go with most of the time, as it is simple and scales:

get_size.py

#!/usr/bin/env python3

import sys

import numpy as np
import matplotlib.pyplot as plt
import matplotlib as mpl

height = int(sys.argv[1])
fig, ax = plt.subplots()
t = np.arange(-10., 10., 1.)
plt.plot(t, t, '.')
plt.plot(t, t**2, '.')
ax.text(0., 60., 'Hello', fontdict=dict(size=25))
plt.savefig(
    'get_size.png',
    format='png',
    dpi=height/fig.get_size_inches()[1]
)

run:

./get_size.py 431

outputs:

get_size.png PNG 574x431 574x431+0+0 8-bit sRGB 10058B 0.000u 0:00.000

https://i.stack.imgur.com/KdCdo.png

and

./get_size.py 1293

outputs:

main.png PNG 1724x1293 1724x1293+0+0 8-bit sRGB 46709B 0.000u 0:00.000

https://i.stack.imgur.com/sitTs.png

I tend to set just the height because I'm usually most concerned about how much vertical space the image is going to take up in the middle of my text.

plt.savefig(bbox_inches='tight' changes image size

I always feel that there is too much white space around images, and tended to add bbox_inches='tight' from: Removing white space around a saved image

However, that works by cropping the image, and you won't get the desired sizes with it.

Instead, this other approach proposed in the same question seems to work well:

plt.tight_layout(pad=1)
plt.savefig(...

which gives the exact desired height for height equals 431:

https://i.stack.imgur.com/tX75f.png

Fixed height, set_aspect, automatically sized width and small margins

Ermmm, set_aspect messes things up again and prevents plt.tight_layout from actually removing the margins... this is an important use case that I don't have a great solution for yet.

Asked at: How to obtain a fixed height in pixels, fixed data x/y aspect ratio and automatically remove remove horizontal whitespace margin in Matplotlib?

plt.savefig(dpi=h/fig.get_size_inches()[1] + width control

If you really need a specific width in addition to height, this seems to work OK:

width.py

#!/usr/bin/env python3

import sys

import numpy as np
import matplotlib.pyplot as plt
import matplotlib as mpl

h = int(sys.argv[1])
w = int(sys.argv[2])
fig, ax = plt.subplots()
wi, hi = fig.get_size_inches()
fig.set_size_inches(hi*(w/h), hi)
t = np.arange(-10., 10., 1.)
plt.plot(t, t, '.')
plt.plot(t, t**2, '.')
ax.text(0., 60., 'Hello', fontdict=dict(size=25))
plt.savefig(
    'width.png',
    format='png',
    dpi=h/hi
)

run:

./width.py 431 869

output:

width.png PNG 869x431 869x431+0+0 8-bit sRGB 10965B 0.000u 0:00.000

https://i.stack.imgur.com/udybG.png

and for a small width:

./width.py 431 869

output:

width.png PNG 211x431 211x431+0+0 8-bit sRGB 6949B 0.000u 0:00.000

https://i.stack.imgur.com/Xbq1g.png

So it does seem that fonts are scaling correctly, we just get some trouble for very small widths with labels getting cut off, e.g. the 100 on the top left.

I managed to work around those with Removing white space around a saved image

plt.tight_layout(pad=1)

which gives:

width.png PNG 211x431 211x431+0+0 8-bit sRGB 7134B 0.000u 0:00.000

https://i.stack.imgur.com/D3Adb.png

From this, we also see that tight_layout removes a lot of the empty space at the top of the image, so I just generally always use it.

Fixed magic base height, dpi on fig.set_size_inches and plt.savefig(dpi= scaling

I believe that this is equivalent to the approach mentioned at: https://stackoverflow.com/a/13714720/895245

magic.py

#!/usr/bin/env python3

import sys

import numpy as np
import matplotlib.pyplot as plt
import matplotlib as mpl

magic_height = 300
w = int(sys.argv[1])
h = int(sys.argv[2])
dpi = 80
fig, ax = plt.subplots(dpi=dpi)
fig.set_size_inches(magic_height*w/(h*dpi), magic_height/dpi)
t = np.arange(-10., 10., 1.)
plt.plot(t, t, '.')
plt.plot(t, t**2, '.')
ax.text(0., 60., 'Hello', fontdict=dict(size=25))
plt.savefig(
    'magic.png',
    format='png',
    dpi=h/magic_height*dpi,
)

run:

./magic.py 431 231

outputs:

magic.png PNG 431x231 431x231+0+0 8-bit sRGB 7923B 0.000u 0:00.000

https://i.stack.imgur.com/cnTUV.png

And to see if it scales nicely:

./magic.py 1291 693

outputs:

magic.png PNG 1291x693 1291x693+0+0 8-bit sRGB 25013B 0.000u 0:00.000

https://i.stack.imgur.com/I5xN6.png

So we see that this approach also does work well. The only problem I have with it is that you have to set that magic_height parameter or equivalent.

Fixed DPI + set_size_inches

This approach gave a slightly wrong pixel size, and it makes it is hard to scale everything seamlessly.

set_size_inches.py

#!/usr/bin/env python3

import sys

import numpy as np
import matplotlib.pyplot as plt
import matplotlib as mpl

w = int(sys.argv[1])
h = int(sys.argv[2])
fig, ax = plt.subplots()
fig.set_size_inches(w/fig.dpi, h/fig.dpi)
t = np.arange(-10., 10., 1.)
plt.plot(t, t, '.')
plt.plot(t, t**2, '.')
ax.text(
    0,
    60.,
    'Hello',
    # Keep font size fixed independently of DPI.
    # https://stackoverflow.com/questions/39395616/matplotlib-change-figsize-but-keep-fontsize-constant
    fontdict=dict(size=10*h/fig.dpi),
)
plt.savefig(
    'set_size_inches.png',
    format='png',
)

run:

./set_size_inches.py 431 231

outputs:

set_size_inches.png PNG 430x231 430x231+0+0 8-bit sRGB 8078B 0.000u 0:00.000

so the height is slightly off, and the image:

https://i.stack.imgur.com/2rC6e.png

The pixel sizes are also correct if I make it 3 times larger:

./set_size_inches.py 1291 693

outputs:

set_size_inches.png PNG 1291x693 1291x693+0+0 8-bit sRGB 19798B 0.000u 0:00.000

https://i.stack.imgur.com/dWsRG.png

We understand from this however that for this approach to scale nicely, you need to make every DPI-dependant setting proportional to the size in inches.

In the previous example, we only made the "Hello" text proportional, and it did retain its height between 60 and 80 as we'd expect. But everything for which we didn't do that, looks tiny, including:

line width of axes

tick labels

point markers

SVG

I could not find how to set it for SVG images, my approaches only worked for PNG e.g.:

get_size_svg.py

#!/usr/bin/env python3

import sys

import numpy as np
import matplotlib.pyplot as plt
import matplotlib as mpl

height = int(sys.argv[1])
fig, ax = plt.subplots()
t = np.arange(-10., 10., 1.)
plt.plot(t, t, '.')
plt.plot(t, t**2, '.')
ax.text(0., 60., 'Hello', fontdict=dict(size=25))
plt.savefig(
    'get_size_svg.svg',
    format='svg',
    dpi=height/fig.get_size_inches()[1]
)

run:

./get_size_svg.py 431

and the generated output contains:

<svg height="345.6pt" version="1.1" viewBox="0 0 460.8 345.6" width="460.8pt"

and identify says:

get_size_svg.svg SVG 614x461 614x461+0+0 8-bit sRGB 17094B 0.000u 0:00.000

and if I open it in Chromium 86 the browser debug tools mouse image hover confirm that height as 460.79.

But of course, since SVG is a vector format, everything should in theory scale, so you can just convert to any fixed sized format without loss of resolution, e.g.:

inkscape -h 431 get_size_svg.svg -b FFF -e get_size_svg.png

gives the exact height:

https://i.stack.imgur.com/i4kHL.png

I use Inkscape instead of Imagemagick's convert here because you need to mess with -density as well to get sharp SVG resizes with ImageMagick:

https://superuser.com/questions/598849/imagemagick-convert-how-to-produce-sharp-resized-png-files-from-svg-files/1602059#1602059

How to convert a SVG to a PNG with ImageMagick?

And setting <img height="" on the HTML should also just work for the browser.

Tested on matplotlib==3.2.2.


P
Peter Mortensen

To increase the size of your figure N times, you need to insert this just before your pl.show():

N = 2
params = pl.gcf()
plSize = params.get_size_inches()
params.set_size_inches((plSize[0]*N, plSize[1]*N))

It also works well with an IPython notebook.


P
Peter Mortensen

The following will surely work, but make sure you add the line plt.figure(figsize=(20,10)) above plt.plot(x,y), plt.pie(), etc.

import matplotlib.pyplot as plt
plt.figure(figsize=(20,10))
plt.plot(x,y) ## This is your plot
plt.show()

The code is copied from amalik2205.


P
Peter Mortensen

Generalizing and simplifying psihodelia's answer:

If you want to change the current size of the figure by a factor sizefactor:

import matplotlib.pyplot as plt

# Here goes your code

fig_size = plt.gcf().get_size_inches() # Get current size
sizefactor = 0.8 # Set a zoom factor
# Modify the current size by the factor
plt.gcf().set_size_inches(sizefactor * fig_size) 

After changing the current size, it might occur that you have to fine tune the subplot layout. You can do that in the figure window GUI, or by means of the command subplots_adjust

For example,

plt.subplots_adjust(left=0.16, bottom=0.19, top=0.82)

C
Community

Since Matplotlib isn't able to use the metric system natively, if you want to specify the size of your figure in a reasonable unit of length such as centimeters, you can do the following (code from gns-ank):

def cm2inch(*tupl):
    inch = 2.54
    if isinstance(tupl[0], tuple):
        return tuple(i/inch for i in tupl[0])
    else:
        return tuple(i/inch for i in tupl)

Then you can use:

plt.figure(figsize=cm2inch(21, 29.7))

P
Peter Mortensen

Use this:

plt.figure(figsize=(width,height))

The width and height are in inches. If not provided, it defaults to rcParams["figure.figsize"] = [6.4, 4.8]. See more here.


P
Peter Mortensen

This resizes the figure immediately even after the figure has been drawn (at least using Qt4Agg/TkAgg - but not Mac OS X - with Matplotlib 1.4.0):

matplotlib.pyplot.get_current_fig_manager().resize(width_px, height_px)

P
Peter Mortensen

Another option is to use the rc() function in Matplotlib (the unit is inch):

import matplotlib
matplotlib.rc('figure', figsize=[10,5])

This is very useful as it assigns the size globally. That way you don't need to specify it for each plot. However, it might be more common to do import matplotlib.pyplot as plt and then do plt.rc('figure', figsize=(10,5)).
A
Ali Muhammad Khowaja

This is How I printed my Custom Graph with Custom Size

import matplotlib.pyplot as plt
from matplotlib.pyplot import figure

figure(figsize=(16, 8), dpi=80)
plt.plot(x_test, color = 'red', label = 'Predicted Price')
plt.plot(y_test, color = 'blue', label = 'Actual Price')
plt.title('Dollar to PKR Prediction')
plt.xlabel('Predicted Price')
plt.ylabel('Actual Dollar Price')
plt.legend()
plt.show()
           

i
iacob

When creating a new figure, you can specify the size (in inches) with the figsize argument:

import matplotlib.pyplot as plt fig = plt.figure(figsize=(w,h))

If you want to modify an existing figure, use the set_size_inches() method:

fig.set_size_inches(w,h)

If you want to change the default figure size (6.4" x 4.8"), use "run commands" rc:

plt.rc('figure', figsize=(w,h))


U
Udesh Ranjan
import random
import math
import matplotlib.pyplot as plt
start=-20
end=20
x=[v for v in range(start,end)]
#sigmoid function
def sigmoid(x):
    return 1/(1+math.exp(x))
plt.figure(figsize=(8,5))#setting the figure size
plt.scatter([abs(v) for v in x],[sigmoid(v) for v in x])
plt.scatter(x,[sigmoid(sigmoid(v)) for v in x])

https://i.stack.imgur.com/3ONu6.png


D
Derrick Kuria

You could also try to initialize this:

import matplotlib as mpl
import matplotlib.pyplot as plt
mpl.rcParams['figure.figsize'] = (8, 6)
mpl.rcParams['axes.grid'] = False

D
Dharman

Here is an example from my own.

Below I've given you your answer, and I've expanded for you to experiment with.

Also note fig size values are measured in inches

import matplotlib.pyplot as plt

data = [2,5,8,10,15] # Random data, can use existing data frame column

fig, axs = plt.subplots(figsize = (20,6)) # This is your answer to resize the figure

# The below will help you expand on your question and resize individual elements within your figure. Experiement with the below parameters.
axs.set_title("Data", fontsize = 17.5)
axs.tick_params(axis = 'x', labelsize = 14)
axs.set_xlabel('X Label Here', size = 15)
axs.tick_params(axis = 'y', labelsize =14)
axs.set_ylabel('Y Label Here', size = 15)

plt.plot(data)

https://i.stack.imgur.com/1qXSP.png


P
Peter Mortensen

I always use the following pattern:

x_inches = 150*(1/25.4)     # [mm]*constant
y_inches = x_inches*(0.8)
dpi = 96

fig = plt.figure(1, figsize = (x_inches,y_inches), dpi = dpi, constrained_layout = True)

With this example you are able to set figure dimensions in inches or in millimetres. When setting constrained_layout to True, plots fill your figure without borders.