close #36

Status

Check the following boxes when they are accurate.

• I have rebased onto the most recent version of master
• I have written new tests for any functionality I added
• This code is no longer a work in progress and is ready for review.

Description

A lineplot is a scatterplot variant where you expect to see the data in a particular order, and the value at x+1 is related to the value at x. There are a couple of interesting attributes of line plots, which seem to be difficult to handle. Here's the working list:

• Create a sample henchman.plotting.lineplot function
• Allow for a sample slider, which downsamples the points resulting in a smoother graph
• Add a docstring for lineplot and a link in the documentation and api reference
• Add tests for lineplot
• Handle categorical labels on the x and y axis
  • This is difficult for two reasons
    1. There's not an col_names for every possible float axis labels (which are autogenerated by bokeh)
    2. There's not necessarily an axis label to replace for the relevant col_names
  • Both can be handled with FixedTicker(ticks=valueslist), but then it's necessary to find how many values are appropriate. That seems to be a hard problem.
• Handle multiple lineplots using the same axes (this is an API question)
• Give the ability to show rate of change, area under curve
• Add an example in the plotting gallery

Given all of those, I'm going to increase the difficulty of the tagged issue.