FIX: fixed plots with few x labels (closes #1076)

gdementen · gdementen · commit cb35dfe64d4e · 2023-10-23T16:02:41.000+02:00
diff --git a/doc/source/changes/version_0_34_2.rst.inc b/doc/source/changes/version_0_34_2.rst.inc
@@ -52,3 +52,7 @@ Fixes
   but this did not: ::
 
     >>> (X.age != 2) * arr
+
+* fixed plots with fewer than 6 integer labels in the x axis. In that case,
+  it interpolated the values, which usually looks wrong for integer labels (e.g. year).
+  Closes :issue:`1076`.
diff --git a/larray/core/plot.py b/larray/core/plot.py
@@ -122,12 +122,22 @@ def _plot_array(array, *args, x=None, y=None, series=None, _x_axes_last=False, *
                 # move label_axis last (it must be a dataframe column)
                 array = array.transpose(..., label_axis)
 
-        lineplot = 'kind' not in kwargs or kwargs['kind'] == 'line'
+        kind = kwargs.get('kind', 'line')
+        if kind is None:
+            kind = 'line'
+        lineplot = kind == 'line'
+        # TODO: why don't we handle all line plots this way?
         if lineplot and label_axis is not None and series is not None and len(series) > 0:
             # the problem with this approach (n calls to pandas.plot) is that the color
             # cycling and "stacked" bar/area of pandas break for all kinds of plots except "line"
             # when we have more than one dimension involved
             for series_key, series_data in array.items(series):
+                # workaround for issue #1076 (see below for more details)
+                # matplotlib default behavior when there are few ticks is to interpolate
+                # them, which looks pretty silly for integer types
+                x_labels = series_data.axes[0].labels
+                if len(x_labels) < 6 and np.issubdtype(x_labels.dtype, np.integer) and 'xticks' not in kwargs:
+                    kwargs['xticks'] = x_labels
                 series_name = ' '.join(str(k) for k in series_key)
                 # support for list-like y
                 if isinstance(y, (list, np.ndarray)):
@@ -145,6 +155,15 @@ def _plot_array(array, *args, x=None, y=None, series=None, _x_axes_last=False, *
                 if not _x_axes_last and label_axis is None:
                     array = array.transpose(..., array.axes[0])
 
+            # workaround for issue #1076 (see above)
+            # We only do it for line and area charts because specifying xticks
+            # breaks bar plots (and bar plots do not suffer from the issue anyway)
+            # (see https://github.com/pandas-dev/pandas/issues/55508)
+            if kind in {'line', 'area'}:
+                x_labels = array.axes[0].labels
+                if len(x_labels) < 6 and np.issubdtype(x_labels.dtype, np.integer) and 'xticks' not in kwargs:
+                    kwargs['xticks'] = x_labels
+
             return PlotObject._to_pd_obj(array).plot(*args, x=x, y=y, **kwargs)
 
     def __call__(self, x=None, y=None, ax=None, subplots=False, layout=None, figsize=None,
