Initial simple plot

Status:

Coding done but remaining issues to look at with reviewer are:

• callback for bvalue: not sure what to do
• how to refactor to make it less ugly and more extendable?

Summary

In order to have more flexible plotting, we need a new data class. This issue is about creating a simple plotting function that uses this class.

Update: Data class idea has been dumped. Now using a dictionary of ColumnDataSource

It will also create a new plotting module.

Design.

Something like

def plot_signal_vs_bval(data, fig, display_options={...}):
   '''Creates a line plot of signal vs bvalue 
      Checks what's in the data
      If it finds 'data_points', it uses scatter plot
      If it finds 'signal', it uses line plot
      would be nice to be able to configure the display as well
   '''
   for src in data.sources:
      if src.dtype == 'data_points':
         fig.circle('bvals','signal',src,**display_options)
      elif src.dtype == 'signal':
         fig.line('bvals','signal',src,**display_options)
      else:
         raise(Exception("src.dtype should be one of 'data_points' or 'signal'"))