ValueError: left cannot be >= right

[dkoppstein]

Hi, I'm getting the following matplotlib error when using FacetGrid with the following invocation:

g = sns.FacetGrid(final_df, col_wrap=3, col='CLONE', size=1, margin_titles=True)
g = g.map(plt.plot, "SUBJECT", "value", marker="o", ms=4)

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-47-f7ad55c8195d> in <module>()
      1 g = sns.FacetGrid(final_df, col_wrap=3, col='CLONE', size=1, margin_titles=True)
----> 2 g = g.map(plt.plot, "SUBJECT", "value", marker="o", ms=4)
      3 g.set_titles(size=5)

/large/dkoppstein/env/conda3/lib/python3.4/site-packages/seaborn/axisgrid.py in map(self, func, *args, **kwargs)
    727 
    728         # Finalize the annotations and layout
--> 729         self._finalize_grid(args[:2])
    730 
    731         return self

/large/dkoppstein/env/conda3/lib/python3.4/site-packages/seaborn/axisgrid.py in _finalize_grid(self, axlabels)
    818         self.set_axis_labels(*axlabels)
    819         self.set_titles()
--> 820         self.fig.tight_layout()
    821 
    822     def facet_axis(self, row_i, col_j):

/large/dkoppstein/env/conda3/lib/python3.4/site-packages/matplotlib/figure.py in tight_layout(self, renderer, pad, h_pad, w_pad, rect)
   1663                                          rect=rect)
   1664 
-> 1665         self.subplots_adjust(**kwargs)
   1666 
   1667 

/large/dkoppstein/env/conda3/lib/python3.4/site-packages/matplotlib/figure.py in subplots_adjust(self, *args, **kwargs)
   1520 
   1521         """
-> 1522         self.subplotpars.update(*args, **kwargs)
   1523         for ax in self.axes:
   1524             if not isinstance(ax, SubplotBase):

/large/dkoppstein/env/conda3/lib/python3.4/site-packages/matplotlib/figure.py in update(self, left, bottom, right, top, wspace, hspace)
    219             if self.left >= self.right:
    220                 reset()
--> 221                 raise ValueError('left cannot be >= right')
    222 
    223             if self.bottom >= self.top:

ValueError: left cannot be >= right

It looks like this is a matplotlib issue with tight_layout; there's a workaround, e.g. here but I don't know how to apply it to the FacetGrid instance.

[mwaskom]

Without seeing your data I'd have to guess but I think something like this can happen if your titles are too big for the facets.

[dkoppstein]

Indeed, your intuition is spot-on and the titles are quite large. Is there a way to decrease the size of the titles prior to plotting? I used g.set_titles(size=2), but I get the error upon creating the FacetGrid.

[mwaskom]

You could change the default axes titlesize with an rcparam context manager or start with a big plot, change the title size, and then change the figure size.

But I doubt that what you really want is titles in 2 pt font, so you might have to rethink the plot you're trying to make.

[dkoppstein]

Indeed, the size=2 was just to try an arbitrarily small number to see if it worked. I'll try setting rcparam prior to instantiating the FacetGrid, thanks for the response.