Seaborn: Seaborn should intelligently label datetime axes

[shoyer]

I'm often interested in plotting data indexed with a pandas.DatetimeIndex object / datetime64 array. It would be nice if seaborn could recognize when the values along an axis are given by dates and provide sensible labels (like pandas).

[mwaskom]

That would be useful I am sure, but since I never work with DateTime objects it would have to come from someone who understands them.

[mwaskom]

Alternatively shouldn't this "just work" upstream, i.e. in matplotlib?

[shoyer]

That's a fair point. Here's the relevant matplotlib issue: https://github.com/matplotlib/matplotlib/issues/1097

[shoyer]

Looking over the pandas documentation, I noticed that it claims to automatically format dates for matplotlib:
http://pandas.pydata.org/pandas-docs/stable/visualization.html#plotting-directly-with-matplotlib

It appears that the trick is that you need to pass in a pandas object (e.g., an Index or Series) directly into the matplotlib function.

For example, deleting 24 characters appears to suffice to get date formatting working with tsplot:
https://github.com/shoyer/seaborn/commit/43969109ab8e7a7ddeb0f1542608ab781e0af918

import seaborn as sns
import pandas as pd
sns.set(style="darkgrid")

gammas = sns.load_dataset("gammas")
gammas['time'] = pd.to_datetime('2000-01-01') + pd.to_timedelta(10, unit='D') * gammas['timepoint']
sns.tsplot(gammas, "time", "subject", "ROI", "BOLD signal")

I have _not_ tested this very carefully yet and it does seem likely that there will be issues, e.g., as noted by this excerpt from axisgrid.py:

            # Some matplotlib functions don't handle pandas objects correctly
            if func.__module__.startswith("matplotlib"):
                plot_args = [v.values for v in plot_args]

            # Draw the plot
            self._facet_plot(func, ax, plot_args, kwargs)

Still, I would love to get this working in the cases where it is feasible.

[mwaskom]

[laurieskelly]

my god @shoyer, i hope you eventually let that poor subject out of the scanner...

[clarkfitzg]

@clearf @shoyer fig.autofmt_xdate() is pretty handy. http://matplotlib.org/users/recipes.html#fixing-common-date-annoyances

[foobarbecue]

Wow, this is still open? Seaborn timeseries plots don't support time axis labels? Maybe nobody wants to fix the issue because every time they come here they have to look at that obnoxious gif...

[mwaskom]

There, now it's closed. Official answer: seaborn is not going to support time axis labels in tsplot, and @foobarbecue is blocked from the repository for being obnoxious.

[joseortiz3]

I think its not difficult to extract the methods pandas uses to make such nice date axes. I was looking at it yesterday, the machinery can be tracked down and extracted, no need to invent the wheel (although attaching this wheel might require a bit of work).

[szeitlin]

@joseortiz3 It would be great if you would open a PR with a fix for this, or at least outline the steps in detail if it's really that straightforward, so someone else can contribute a fix.

[mwaskom]

This is an issue about a deprecated function so I am locking it.