title: How to show label names in pandas groupby histogram plot
body: <p>I can plot multiple histograms in a single plot using pandas but there are few things missing:</p>
  
  <ol>
  <li>How to give the label.</li>
  <li>I can only plot one figure, how to change it to layout=(3,1) or something else.</li>
  <li>Also, in figure 1, all the bins are filled with solid colors, and its kind of difficult to know which is which, how to fill then with different markers (eg. crosses,slashes,etc)?</li>
  </ol>
  
  <p>Here is the MWE:</p>
  
  <pre><code>import numpy as np
  import pandas as pd
  import seaborn as sns
  import matplotlib.pyplot as plt
  
  df = sns.load_dataset('iris')
  
  df.groupby('species')['sepal_length'].hist(alpha=0.7,label='species')
  plt.legend()
  </code></pre>
  
  <p>Output:
  <a href="https://i.stack.imgur.com/VsR4f.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/VsR4f.png" alt="enter image description here"></a></p>
  
  <h1>To change layout I can use by keyword, but can't give them colors</h1>
  
  <p>HOW TO GIVE DIFFERENT COLORS?</p>
  
  <pre><code>df.hist('sepal_length',by='species',layout=(3,1))
  plt.tight_layout()
  </code></pre>
  
  <p>Gives:
  <a href="https://i.stack.imgur.com/dADTD.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/dADTD.png" alt="enter image description here"></a></p>