How to force the Y axis to only use integers in Matplotlib

I’m plotting a histogram using the matplotlib.pyplot module and I am wondering how I can force the y-axis labels to only show integers (e.g. 0, 1, 2, 3 etc.) and not decimals (e.g. 0., 0.5, 1., 1.5, 2. etc.).

I’m looking at the guidance notes and suspect the answer lies somewhere around matplotlib.pyplot.ylim but so far I can only find stuff that sets the minimum and maximum y-axis values.

def doMakeChart(item, x):
    if len(x)==1:
        return
    filename = "C:Usersmemaxbyte3charts\"
    bins=logspace(0.1, 10, 100)
    plt.hist(x, bins=bins, facecolor='green', alpha=0.75)
    plt.gca().set_xscale("log")
    plt.xlabel('Size (Bytes)')
    plt.ylabel('Count')
    plt.suptitle(r'Normal Distribution for Set of Files')
    plt.title('Reference PUID: %s' % item)
    plt.grid(True)
    plt.savefig(filename + item + '.png')
    plt.clf()

Answers:

Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

Here is another way:

from matplotlib.ticker import MaxNLocator

ax = plt.figure().gca()
ax.yaxis.set_major_locator(MaxNLocator(integer=True))

Method 2

If you have the y-data

y = [0., 0.5, 1., 1.5, 2., 2.5]

You can use the maximum and minimum values of this data to create a list of natural numbers in this range. For example,

import math
print range(math.floor(min(y)), math.ceil(max(y))+1)

yields

[0, 1, 2, 3]

You can then set the y tick mark locations (and labels) using matplotlib.pyplot.yticks:

yint = range(min(y), math.ceil(max(y))+1)

matplotlib.pyplot.yticks(yint)

Method 3

this works for me:

import matplotlib.pyplot as plt
plt.hist(...

# make the y ticks integers, not floats
yint = []
locs, labels = plt.yticks()
for each in locs:
    yint.append(int(each))
plt.yticks(yint)

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0