Re: [Matplotlib-users] manipulating histogram data from hist function

[Paul I. <piv...@gm...>]

Philippe Piot, on 2010-12-27 13:58,  wrote:
> 1/  When executing the above script, I also display the histograms
> generated when invoking "hist" (I tried to make this line tranparaent
> by using alpha=0 but it did not work).

Hi Philippe,

welcome to matplotlib - I think what you really want to do is
just use numpy's histogram function, and then plot the result.
This is actually the function matplotlib's hist uses behind the
scenes.

> 2/ can I directly manipulate the data within an histogram to
> arbitrarily offset the histogram?

Once you get the histogram using numpy, you can plot it in in any
way you want. Here's a small example:

  import numpy as np
  import matplotlib.pyplot as plt
  h,edges = np.histogram(np.random.randn(1000))
  plt.bar(edges[:-1],h, width=edges[1]-edges[0])
  plt.bar(edges[:-1]-10,h, width=edges[1]-edges[0]) #offset
  plt.step(edges[1:],h) # plot as step lines instead of bars
  plt.step(edges[1:]+10,h) # same as above, with an offset

best,
-- 
Paul Ivanov
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