How can I save histogram plot in python?

Question

I have following code that generates a histogram. How can I save the histogram automatically using the code? I tried what we do for other plot types but that did not work for histogram.a is a 'numpy.ndarray'.

a = [-0.86906864 -0.72122614 -0.18074998 -0.57190212 -0.25689268 -1.
     0.68713553  0.29597819  0.45022949  0.37550592  0.86906864  0.17437203
     0.48704826  0.2235648   0.72122614  0.14387731  0.94194514 ]

fig = pl.hist(a,normed=0)
pl.title('Mean')
pl.xlabel("value")
pl.ylabel("Frequency")
pl.savefig("abc.png")

zdim · Accepted Answer · 2018-03-18 19:02:00Z

15

This works for me:

import matplotlib.pyplot as pl
import numpy as np

a = np.array([-0.86906864, -0.72122614, -0.18074998, -0.57190212, -0.25689268 ,-1. ,0.68713553 ,0.29597819, 0.45022949, 0.37550592, 0.86906864, 0.17437203, 0.48704826, 0.2235648, 0.72122614, 0.14387731, 0.94194514])

fig = pl.hist(a,normed=0)
pl.title('Mean')
pl.xlabel("value")
pl.ylabel("Frequency")
pl.savefig("abc.png")

a in the OP is not a numpy array and its format also needs to be modified (it needs commas, not spaces as delimiters). This program successfully saves the histogram in the working directory. If it still does not work, supply it with a full path to the location where you want to save it like this

pl.savefig("/Users/atru/abc.png")

The pl.show() statement should not be placed before savefig() as it creates a new figure which makes savefig() save a blank figure instead of the desired one as explained in this post.

edited Mar 18, 2018 at 19:02

zdim

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answered Sep 25, 2017 at 18:19

atru

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14 Comments

A.S Over a year ago

@ atru: Yes, I am using matplotlib. I tried the way you suggested but it saves an empty png file.

atru Over a year ago

Can you share more of your code then? It works perfect for me. In fact I was pretty happy with the quality.

A.S Over a year ago

@ atru: I have edited the code in the question section with savefig. Please take a look. Thank you

atru Over a year ago

Briefly scrolling through this post and checking it out - do you have a pl.show() before pl.savefig() ?

A.S Over a year ago

I just realized this too. I have pl.show() before pl.savefig(). I switched those lines of code and now it works fine. Thank you very much.

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