title: Plotting GroupBy Object in Pandas
body: <p>I have a dataframe with various parameters (continuous time-series data) and other columns to filter out various conditions; these are made up of <code>1</code> when the condition is true and <code>NaN</code> when the condition is false.</p>
  
  <p>If I plot a parameter and then plot it again just in the gate, I can do:</p>
  
  <pre><code>df.parameter.plot()
  df.groupby('filter_column').parameter.plot(style='bo')
  </code></pre>
  
  <p>This example works fine, but if I want to plot using a line (<code>style='b-'</code> for example) it then joins the groups of filtered data with a line</p>
  
  <p>A work-around is to create intermediate series, or multiply the two columns within a matplotlib call:</p>
  
  <pre><code>series = df.parameter * df.filter_column
  series.plot(style='b-')
  
  plt.plot(df.parameter * df.filter_column,'b-')
  </code></pre>
  
  <p>I'm not a fan of this type of plot statement or creating the intermediate columns. It would be really useful to have the direct <code>groupby</code> line plot deal with the NAs in the same way as a series.</p>
  
  <p>Does anyone have any more elegant workarounds for this?</p>