python plot simple histogram given binned data

Question

I have count data (a 100 of them), each correspond to a bin (0 to 99). I need to plot these data as histogram. However, histogram count those data and does not plot correctly because my data is already binned.

import random import matplotlib.pyplot as plt x = random.sample(range(1000), 100) xbins = [0, len(x)] #plt.hist(x, bins=xbins, color = 'blue')  #Does not make the histogram correct. It counts the occurances of the individual counts.   plt.plot(x) #plot works but I need this in histogram format plt.show() 

Answer 1

If I'm understanding what you want to achieve correctly then the following should give you what you want:

import matplotlib.pyplot as plt plt.bar(range(0,100), x) plt.show() 

It doesn't use hist(), but it looks like you've already put your data into bins so there's no need.

Answer 2

The problem is with your xbins. You currently have

xbins = [0, len(x)] 

which will give you the list [0, 100]. This means you will only see 1 bin (not 2) bounded below by 0 and above by 100. I am not totally sure what you want from your histogram. If you want to have 2 unevenly spaced bins, you can use

xbins = [0, 100, 1000] 

to show everything below 100 in one bin, and everything else in the other bin. Another option would be to use an integer value to get a certain number of evenly spaced bins. In other words do

plt.hist(x, bins=50, color='blue') 

where bins is the number of desired bins.

On a side note, whenever I can't remember how to do something with matplotlib, I will usually just go to the thumbnail gallery and find an example that looks more or less what I am trying to accomplish. These examples all have accompanying source code so they are quite helpful. The documentation for matplotlib can also be very handy.