title: Plot histogram with index values on x axis and frequencies of each column value on y axis
body: <p>Based on the dataframe </p>
  
  <pre><code>import pandas as pd
  df = pd.DataFrame({'cat1':[100,0,0,5],'cat2':[5,20,50,0]})
  df 
      cat1    cat2
  0   100 5
  1   0   20
  2   0   50
  3   5   0
  </code></pre>
  
  <p>I want to plot a histogram such that the x axis represent the index values 0 to 3 and the bars for each index value show the distribution of the column values cat1 and cat2. </p>
  
  <pre><code>df.plot.hist(alpha=0.5)
  </code></pre>
  
  <p>plots the index values on the y and the category values on the x axis: </p>
  
  <p><a href="https://i.stack.imgur.com/tHNhM.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/tHNhM.png" alt="enter image description here"></a></p>
  
  <p>And </p>
  
  <pre><code>df.transpose().plot.hist(alpha=0.5)
  </code></pre>
  
  <p>results in something I don't even fully understand:</p>
  
  <p><a href="https://i.stack.imgur.com/WNKGO.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/WNKGO.png" alt="enter image description here"></a></p>
  
  <p>What I actually want is a bar for each index value, that illustrates the values in the columns - e.g. for index 0, there should be a bar in cat1 color stretching to 100 on the y axis, containing another bar in cat2 color stretching to 5. </p>
  
  <p>How can I achieve that? </p>