fixed slopegraph_kwargs

fixed a bug when using the `slopegraph_kwargs`. Also added documentation for the `slopegraph_kwargs`

Author: DizietAsahi

dabest/_classes.py

@@ -1209,6 +1209,12 @@ def plot(self, color_col=None,
             pyplot.violinplot` command here, as a dict. If None, the following
             keywords are passed to violinplot : {'widths':0.5, 'vert':True,
             'showextrema':False, 'showmedians':False}.
+        slopegraph_kwargs : dict, default None
+            This will change the appearance of the lines used to join each pair
+            of observations when `show_pairs=True`. Pass any keyword arguments
+            accepted by matplotlib `plot()` function here, as a dict.
+            If None, the following keywords are
+            passed to plot() : {'linewidth':1, 'alpha':0.5}.
         reflines_kwargs : dict, default None
             This will change the appearance of the zero reference lines. Pass
             any keyword arguments accepted by the matplotlib Axes `hlines`

dabest/plotter.py

@@ -130,7 +130,7 @@ def EffectSizeDataFramePlotter(EffectSizeDataFrame, **plot_kwargs):
     if plot_kwargs["slopegraph_kwargs"] is None:
         slopegraph_kwargs = default_slopegraph_kwargs
     else:
-        slopegraph_kwargs = merge_two_dicts(slopegraph_kwargs,
+        slopegraph_kwargs = merge_two_dicts(default_slopegraph_kwargs,
                                             plot_kwargs["slopegraph_kwargs"])