How do I equalize the scales of the x-axis and y-axis?

Question

How do I create a plot where the scales of x-axis and y-axis are the same?

This equal ratio should be maintained even if I change the window size. Currently, my graph scales together with the window size.

I tried:

plt.xlim(-3, 3)
plt.ylim(-3, 3)
plt.axis('equal')

Democracy

for 3d, you have to do a little bit extra work: #13685886 – Chiba

Answer 1

Use Axes.set_aspect in the following manner:

from matplotlib import pyplot as plt
plt.plot(range(5))
plt.xlim(-3, 3)
plt.ylim(-3, 3)
ax = plt.gca()
ax.set_aspect('equal', adjustable='box')
plt.draw()

Modify

Awesome! It indeed works like charm. Could you please tell me what plt.plot(range(5)) and plt.gca().set_aspect('equal', adjustable='box') do, if you don't mind? Also, I notice that even if I don't have plt.draw(), the plot will still show up. Then what is the use of it? – Democracy

the plot is just have something to show. For the set_aspect read the documentation link. The draw is just to make sure it gets rendered. – Modify

Sorry but I am asking about the range(5) thing inside plot(). What does the range(5) do? – Democracy

ah, range(5) returns [0, 1, 2, 3, 4] See: docs.python.org/2/library/functions.html#range – Modify

yah, I know it returns that, but then why do I feed the list to plot()? – Democracy

to have some fake data to plot (it should have plotted a straight line). – Modify

@perfectionm1ng no worries, took me a while to figure out what you were asking. – Modify

I don't see the need to set both limits to the same ranges, this can result in different scales, especially when most plots are not square shaped. – Goulder

Is there a way to get this done without having to specify exactly the limits? I would have expected there to be a simple command to get a square plot with the same scale and ticks for both axis. Thanks – Billionaire

@Confounded: As stated below, if you don't want to give any limits you can just use plt.axis('square') – Demonize

This is really great, thank you. For a specific subplot you can also do ax.set_aspect('equal', adjustable='box') – Parental

how in the name of all that is good and true is this not the default ? I tremble to wonder how many bad decisions have been made as a result of looking at data with incorrectly scaled axes... – Harbert

Answer 2

plt.axis('scaled')

works well for me.

Ethos

Also worked for me. Just make sure to use this before setting limits/ticks, as it will rescale automatically. – Stalk

Sorry, plt.axis('scaled') didn't work for me in Python 3.7 and matplotlib - matplotlib==3.1.0 However, plt.axis('square') worked! – Kimbrough

@rishijain ValueError: Unrecognized string squared to axis; try on or off – Osmium

@MonaJalal it's plt.axis('square') not plt.axis('squared') – Delorenzo

Answer 3

See the documentation on plt.axis(). This:

plt.axis('equal')

doesn't work because it changes the limits of the axis to make circles appear circular. What you want is:

plt.axis('square')

This creates a square plot with equal axes.

Hyacinth

Answer 4

Try something like:

import pylab as p
p.plot(x,y)
p.axis('equal')
p.show()

Dealing

This works on my system, perhaps you could show a portion of the code you are working on? Might be able to help work out the issue quicker. – Dealing

This does NOT work in general. The axes are equal, but the plot is not square, unless the plotting window is also square. Tested with Matplotlib 2.0 – Phenyl

P.axis('equal') seems to be like P.gca().set_aspect('equal', adjustable='datalim'). While if adjustable='box', then the plot becomes square. – Metathesize

I definitely do not get a square box out of this. – Purpurin

pylab is deprecated – Weir

If you want to also have the grid square, in addition to aspect as mentioned in the other answers, see https://mcmap.net/q/120267/-square-major-minor-grid-for-axes-with-different-limits – Glaciology

@PeterDrake: The goal isn't to get a square box, but to have the same scale in the x and y axes. So circles will be displayed as circles, but if you don't plot a square or any object with the same width as the height, you won't get a square box either. – Mannuela