# Creating a comparison plot (.PairGrid()) of all my cities' and global data's average percent change in temperature

# Set up my figure by naming it 'pct_chg_yrly_fig', then call PairGrid on the DataFrame
pct_chg_yrly_fig = sns.PairGrid(comp_pct_chg_df.dropna())

# Using map_upper we can specify what the upper triangle will look like.
pct_chg_yrly_fig.map_upper(plt.scatter,color='purple')

# We can also define the lower triangle in the figure, including the plot type (KDE) or the color map (BluePurple)
pct_chg_yrly_fig.map_lower(sns.kdeplot,cmap='cool_d')

# Finally we'll define the diagonal as a series of histogram plots of the yearly average percent change in temperature
pct_chg_yrly_fig.map_diag(plt.hist,histtype='step',linewidth=3,bins=30)

# Adding a legend
pct_chg_yrly_fig.add_legend()

Here is the ValueError msg I'm receiving:

ValueError                                Traceback (most recent call last)
<ipython-input-38-3fcf1b69d4ef> in <module>()
     11
     12 # Finally we'll define the diagonal as a series of histogram plots of the yearly average percent change in temperature
---> 13 pct_chg_yrly_fig.map_diag(plt.hist,histtype='step',linewidth=3,bins=30)
     14
     15 # Adding a legend

~/anaconda3/lib/python3.6/site-packages/seaborn/axisgrid.py in map_diag(self, func, **kwargs)
   1361
   1362                 if "histtype" in kwargs:
-> 1363                     func(vals, color=color, **kwargs)
   1364                 else:
   1365                     func(vals, color=color, histtype="barstacked", **kwargs)

~/anaconda3/lib/python3.6/site-packages/matplotlib/pyplot.py in hist(x, bins, range, density, weights, cumulative, bottom, histtype, align, orientation, rwidth, log, color, label, stacked, normed, hold, data, **kwargs)
   3023                       histtype=histtype, align=align, orientation=orientation,
   3024                       rwidth=rwidth, log=log, color=color, label=label,
-> 3025                       stacked=stacked, normed=normed, data=data, **kwargs)
   3026     finally:
   3027         ax._hold = washold

~/anaconda3/lib/python3.6/site-packages/matplotlib/__init__.py in inner(ax, *args, **kwargs)
   1715                     warnings.warn(msg % (label_namer, func.__name__),
   1716                                   RuntimeWarning, stacklevel=2)
-> 1717             return func(ax, *args, **kwargs)
   1718         pre_doc = inner.__doc__
   1719         if pre_doc is None:

~/anaconda3/lib/python3.6/site-packages/matplotlib/axes/_axes.py in hist(***failed resolving arguments***)
   6137             color = mcolors.to_rgba_array(color)
   6138             if len(color) != nx:
-> 6139                 raise ValueError("color kwarg must have one color per dataset")
   6140
   6141         # If bins are not specified either explicitly or via range,

ValueError: color kwarg must have one color per dataset