title: How to draw an histogram with multiple categories in python
body: <p>I am a freshman in python, and I have a problem of how to draw a histogram in python.</p>
  
  <p>First of all, I have ten intervals that are divided evenly according to the length of flowers' petal, from min to max. Thus I can separate flowers into ten intervals based on petals.</p>
  
  <p>The number of flowers' kind is three, so I want to draw a histogram to describe the distribution of different kinds of flowers in different intervals(bins). And in the same bin, different flowers have different colors. </p>
  
  <p>I know the <code>hist</code> functions in Matplotlib, but I don't know how to use it to draw pictures like below.</p>
  
  <p><a href="https://i.stack.imgur.com/0th1N.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/0th1N.png" alt="wanted histogram"></a></p>
  
  <p>The data are <code>Lbins = [0.1 , 0.34, 0.58, 0.82, 1.06, 1.3 , 1.54, 1.78, 2.02, 2.26, 2.5 ]</code> and  <code>Data_bins</code> is an array of shape (number of flowers, 3).</p>