title: Plotting strings as axis in matplotlib
body: <p>I have a pandas DataFrame similar to :</p>
  
  <pre><code>Species  Count1 Count2 
  AGREP      2       10
  GYLEP      4       6
  POAPRA     2       8
  EUPESU     1       11
  </code></pre>
  
  <p>and I want to make a line plot of species vs. Count 1 with the x-axis being the species and the y-axis as Count 1.</p>
  
  <p>I try to use the code:</p>
  
  <pre><code>import matplotlib.pyplot as plt
  plt.plot(df.Species,df.Count1)
  </code></pre>
  
  <p>but this returns the error:</p>
  
  <pre><code>ValueError: could not convert string to float
  </code></pre>
  
  <p>I want to eventually only chose certain species to plot as well against both counts.  For example, I want to plot <code>AGREP</code> and <code>EUPESUS</code> on the x axis against both Count 1 and Count 2 as the y axis.  Again though, it won't plot the string as the axis name.  </p>