title: Histogram of a pandas dataframe
body: <p>I couldn't find anywhere on the site a similar question.</p>
  
  <p>I have a fairly large file, with over 100000 lines and I read it using pandas:</p>
  
  <pre><code>df = pd.read_excel("somefile.xls",index_col='Offense Type')
  </code></pre>
  
  <p>ended up with a dataframe consisting of the first column (the index column) and another column, 'Offense_type' and 'Hour' respectively.</p>
  
  <p>'Offense Type' consists of a series of "cathegories" say cat1, cat2, cat3, etc...
  'Hour' consists of a series of integer numbers between 1 and 24.</p>
  
  <p>What I would like to do is obtain a histogram of the ocurrences of each number in the dataframe (there aren't that many cathegories It's at most 10 of them)</p>
  
  <p>Here's an ASCII representation of what I want to get"</p>
  
  <p><em>(the x's represent the bars in the histogram, they will surely be at a much higher value than 1,2 or 3)</em></p>
  
  <pre><code>   x        x         # And so on
   x x  x     x x  x    #
   x x  x  x  x x  x    #
   1 2 11 20  5 8 18    #
     Cat1      Cat2     #
  </code></pre>
  
  <p>But i'm getting a single barplot for every line in df using:</p>
  
  <pre><code>df.plot(kind='bar')
  </code></pre>
  
  <p>which is basically unreadable:</p>
  
  <p><img src="https://i.stack.imgur.com/cSDWj.png" alt="histogram_of_dataframe"></p>
  
  <p>I've also tried with the hist() and Histogram() function with no luck.</p>
  
  <p>Here's some sample data:</p>
  
  <p><img src="https://i.stack.imgur.com/DFL5T.png" alt="sample_data"></p>