BUG: Generate the tick position in BarPlot using convert tools from matlab.

Generate the tick position in BarPlot using convert tools from matlab.

Author: nrebena

pandas/plotting/_matplotlib/core.py

@@ -1308,7 +1308,6 @@ def __init__(self, data, **kwargs):
         self.bar_width = kwargs.pop("width", 0.5)
         pos = kwargs.pop("position", 0.5)
         kwargs.setdefault("align", "center")
-        self.tick_pos = np.arange(len(data))
 
         self.bottom = kwargs.pop("bottom", 0)
         self.left = kwargs.pop("left", 0)
@@ -1331,7 +1330,7 @@ def __init__(self, data, **kwargs):
                 self.tickoffset = self.bar_width * pos
                 self.lim_offset = 0
 
-        self.ax_pos = self.tick_pos - self.tickoffset
+        self.ax_index = self.data.index
 
     def _args_adjust(self):
         if is_list_like(self.bottom):
@@ -1358,6 +1357,16 @@ def _make_plot(self):
 
         for i, (label, y) in enumerate(self._iter_data(fillna=0)):
             ax = self._get_ax(i)
+
+            if self.orientation == 'vertical':
+                ax.xaxis.update_units(self.ax_index)
+                self.tick_pos = ax.convert_xunits(self.ax_index)
+                self.ax_pos = self.tick_pos - self.tickoffset
+            elif self.orientation == 'horizontal':
+                ax.yaxis.update_units(self.ax_index)
+                self.tick_pos = ax.convert_yunits(self.ax_index)
+                self.ax_pos = self.tick_pos - self.tickoffset
+
             kwds = self.kwds.copy()
             if self._is_series:
                 kwds["color"] = colors
@@ -1429,8 +1438,8 @@ def _post_plot_logic(self, ax, data):
             str_index = [pprint_thing(key) for key in range(data.shape[0])]
         name = self._get_index_name()
 
-        s_edge = self.ax_pos[0] - 0.25 + self.lim_offset
-        e_edge = self.ax_pos[-1] + 0.25 + self.bar_width + self.lim_offset
+        s_edge = self.ax_pos.min() - 0.25 + self.lim_offset
+        e_edge = self.ax_pos.max() + 0.25 + self.bar_width + self.lim_offset
 
         self._decorate_ticks(ax, name, str_index, s_edge, e_edge)