Color by factor/group when plotting
Hi everyone!

Sorry if this is not the correct place to write this, I'm new to GitHub.

I'm really enjoying pandas but I think there is a basic feature it does not implement, which is
easily color by factor when plotting a dataframe. At least I didn't be able to find how this could be done in a "Pythonic" way.

Say we have a dataframe with data records from weather stations. Different columns have the location of hundreds of stations and rows have measurements for different days of the month (say 30 rows). There is an additional column "Continent" that points which continent each weather station belongs to. Or maybe a separated Series object "as.type('categorical')"

The point is that it should be easy to plot this dataframe, keeping my data separated while coloring and labeling in legend with different colors for different groups, in this case 5 continents, so 5 colors and 5 legend labels.

I'm able to do this with some code, but I think it would be nice to have a feature like:

df.plot(color_by_group=df.Continent) or similar.

PD: Sorry if this, or anything really similar is already implemented.
