I want to put multiple lines on the same plot, but use only part of the data available for some of the lines. Each dataset contains data from 1925 until the present, and I'd like the x-axis to show that entire range, but I only want to show dataset A from 1925 until 1940, dataset B from 1941 to 1958, and so on. In other words, I want to set limits on the data itself, not the axis.
fig, ax = plt.subplots(figsize=(15,10))
plt.plot_date(DF['date'], DF['data1'], '.')
plt.plot_date(DF['date'], DF['data2'], '.')
plt.plot_date(DF['date'], DF['data3'], '.')
plt.plot_date(DF['date'], DF['data4'], '.')
ylabel('Mean Streambed Elevation (feet)')
There are many ways to select subsets of a pandas dataframe, assuming that's what you have.
For instance something like
data_for_plotting=DF.query("date>'1925-01-01' and date<'1940-01-01'")
Then pass that instead of DF to the rest of the plotting statements.
You can look at http://pandas.pydata.org/pandas-docs/stable/indexing.html for other ways to do the same thing.