Propagate minpos from Collections to Axes.dataLim.

This ensures that autoscaling on log scales is correct.

Author: QuLogic

lib/matplotlib/axes/_base.py

@@ -2000,7 +2000,13 @@ def add_collection(self, collection, autolim=True):
             # Make sure viewLim is not stale (mostly to match
             # pre-lazy-autoscale behavior, which is not really better).
             self._unstale_viewLim()
-            self.update_datalim(collection.get_datalim(self.transData))
+            datalim = collection.get_datalim(self.transData)
+            # By definition, p0 <= minpos <= p1, so minpos would be
+            # unnecessary. However, we add minpos to the call so that
+            # self.dataLim will update its own minpos. This ensures that log
+            # scales see the correct minimum.
+            self.update_datalim(
+                np.row_stack([datalim.p0, datalim.minpos, datalim.p1]))
 
         self.stale = True
         return collection

lib/matplotlib/collections.py

@@ -274,11 +274,11 @@ def get_datalim(self, transData):
                 # can properly have the axes limits set by their shape +
                 # offset.  LineCollections that have no offsets can
                 # also use this algorithm (like streamplot).
-                result = mpath.get_path_collection_extents(
-                    transform.get_affine(), paths, self.get_transforms(),
+                return mpath.get_path_collection_extents(
+                    transform.get_affine() - transData, paths,
+                    self.get_transforms(),
                     transOffset.transform_non_affine(offsets),
                     transOffset.get_affine().frozen())
-                return result.transformed(transData.inverted())
             if not self._offsetsNone:
                 # this is for collections that have their paths (shapes)
                 # in physical, axes-relative, or figure-relative units
@@ -290,9 +290,9 @@ def get_datalim(self, transData):
                 # note A-B means A B^{-1}
                 offsets = np.ma.masked_invalid(offsets)
                 if not offsets.mask.all():
-                    points = np.row_stack((offsets.min(axis=0),
-                                           offsets.max(axis=0)))
-                    return transforms.Bbox(points)
+                    bbox = transforms.Bbox.null()
+                    bbox.update_from_data_xy(offsets)
+                    return bbox
         return transforms.Bbox.null()
 
     def get_window_extent(self, renderer):

lib/matplotlib/path.py

@@ -1042,4 +1042,4 @@ def get_path_collection_extents(
     extents, minpos = _path.get_path_collection_extents(
         master_transform, paths, np.atleast_3d(transforms),
         offsets, offset_transform)
-    return Bbox.from_extents(*extents)
+    return Bbox.from_extents(*extents, minpos=minpos)

lib/matplotlib/transforms.py

@@ -808,13 +808,17 @@ def from_bounds(x0, y0, width, height):
         return Bbox.from_extents(x0, y0, x0 + width, y0 + height)
 
     @staticmethod
-    def from_extents(*args):
+    def from_extents(*args, minpos=None):
         """
         Create a new Bbox from *left*, *bottom*, *right* and *top*.
 
-        The *y*-axis increases upwards.
+        The *y*-axis increases upwards. Optionally, passing *minpos* will set
+        that property on the returned Bbox.
         """
-        return Bbox(np.reshape(args, (2, 2)))
+        bbox = Bbox(np.reshape(args, (2, 2)))
+        if minpos is not None:
+            bbox._minpos[:] = minpos
+        return bbox
 
     def __format__(self, fmt):
         return (