513
votes

I need help with setting the limits of y-axis on matplotlib. Here is the code that I tried, unsuccessfully.

import matplotlib.pyplot as plt

plt.figure(1, figsize = (8.5,11))
plt.suptitle('plot title')
ax = []
aPlot = plt.subplot(321, axisbg = 'w', title = "Year 1")
ax.append(aPlot)
plt.plot(paramValues,plotDataPrice[0], color = '#340B8C', 
     marker = 'o', ms = 5, mfc = '#EB1717')
plt.xticks(paramValues)
plt.ylabel('Average Price')
plt.xlabel('Mark-up')
plt.grid(True)
plt.ylim((25,250))

With the data I have for this plot, I get y-axis limits of 20 and 200. However, I want the limits 20 and 250.

9
Works for me with Matplotlib 1.0.0 if I add plt.show() at the end to show the plot. Which version and which backend are you using?Tamás
Working for me with Matplotlib 0.98.5.2, Python 2.6.2. I tried both plt.ylim((25,250)) and plt.ylim(ymax = 250, ymin = 25). I am using the Agg backend.Manoj Govindan
Thanks to both of you. Does it work with PDF backend for you.Curious2learn
note: axisbg is now deprecatedSherylHohman
plt.ylim is the correct, modern solution to this problem. Here is a good resource: showmecode.info/matplotlib/axes/set-limitsluc

9 Answers

750
votes

Try this . Works for subplots too .

axes = plt.gca()
axes.set_xlim([xmin,xmax])
axes.set_ylim([ymin,ymax])
140
votes

Another workaround is to get the plot's axes and reassign changing only the y-values:

x1,x2,y1,y2 = plt.axis()  
plt.axis((x1,x2,25,250))
113
votes

One thing you can do is to set your axis range by yourself by using matplotlib.pyplot.axis.

matplotlib.pyplot.axis

from matplotlib import pyplot as plt
plt.axis([0, 10, 0, 20])

0,10 is for x axis range. 0,20 is for y axis range.

or you can also use matplotlib.pyplot.xlim or matplotlib.pyplot.ylim

matplotlib.pyplot.ylim

plt.ylim(-2, 2)
plt.xlim(0,10)
39
votes

You can instantiate an object from matplotlib.pyplot.axes and call the set_ylim() on it. It would be something like this:

import matplotlib.pyplot as plt
axes = plt.axes()
axes.set_ylim([0, 1])
24
votes

This worked at least in matplotlib version 2.2.2:

plt.axis([None, None, 0, 100])

Probably this is a nice way to set up for example xmin and ymax only, etc.

19
votes

Just for fine tuning. If you want to set only one of the boundaries of the axis and let the other boundary unchanged, you can choose one or more of the following statements

plt.xlim(right=xmax) #xmax is your value
plt.xlim(left=xmin) #xmin is your value
plt.ylim(top=ymax) #ymax is your value
plt.ylim(bottom=ymin) #ymin is your value

Take a look at the documentation for xlim and for ylim

17
votes

To add to @Hima's answer, if you want to modify a current x or y limit you could use the following.

import numpy as np # you probably alredy do this so no extra overhead
fig, axes = plt.subplot()
axes.plot(data[:,0], data[:,1])
xlim = axes.get_xlim()
# example of how to zoomout by a factor of 0.1
factor = 0.1 
new_xlim = (xlim[0] + xlim[1])/2 + np.array((-0.5, 0.5)) * (xlim[1] - xlim[0]) * (1 + factor) 
axes.set_xlim(new_xlim)

I find this particularly useful when I want to zoom out or zoom in just a little from the default plot settings.

10
votes

This should work. Your code works for me, like for Tamás and Manoj Govindan. It looks like you could try to update Matplotlib. If you can't update Matplotlib (for instance if you have insufficient administrative rights), maybe using a different backend with matplotlib.use() could help.

-1
votes

If an axes (generated by code below the code shown in the question) is sharing the range with the first axes, make sure that you set the range after the last plot of that axes.