title: graphing multiple types of plots (line, scatter, bar etc) in the same window
body: <p>I'm trying to graph two types of plots in the same window (i.e. a line plot, and a scatter plot). The data being plotted in the line graph (first plot) are floating numerical values representing climate indices (Y) vs. decimal years (X). The second plot that  I would like to be a 'scatter'ed is much the same, but with floating numerical values representing stream flows (Y) vs. decimal years (X). I've tried to accomplish this as follows by using a twin x axis and a second, parasite y axis for the scatter plot: </p>
  
  <pre><code>    import mpl_toolkits
      from mpl_toolkits.axes_grid1 import host_subplot
      import matplotlib.pyplot as plt
  
      host = host_subplot(111)
      par = host.twinx()
  
      host.set_xlim(1880, 2020)
      host.set_ylim(-5, 10)
  
      host.set_xlabel("Time")
      host.set_ylabel("PDSI Region 01")
      par.set_ylabel("Minimum 10% Annual 7-day Non-exceedance Flow (cfs)")
  
      x1 = timearray
      y1 = pdsiarray01
      x2 = upAmm_yr
      y2 = upAmm_min
  
      p1, = host.plot(x1, y1, label="PDSI01")
      p2, = par.scatter(x2, y2, label="Annual Lowflow Upper Amm")
  
      par.set_ylim(30, 60)
  
      host.legend()
      host.axis["left"].label.set_color(p1.get_color())
      par.axis["right"].label.set_color(p2.get_color())
  
      plt.draw()
      plt.show()
  </code></pre>
  
  <p>and I get the error code:</p>
  
  <pre><code>    TypeError: cannot perform reduce with flexible type
  </code></pre>
  
  <p>This code works fine when I replace scatter with plot in the line that starts with p2, but produces a second line plot. The ultimate reason I want it scattered is that there are many fewer points to be plotted in the second dataset, and the lines connecting them are distracting and 'messy' (when I all need is to highlight an instant in time). A bar plot instead of a scatter would work too. Any suggestions or help would be much appreciated!</p>