matplotlib · jklymak · Mar 14, 2018 · Mar 11, 2018 · Mar 12, 2018
diff --git a/lib/mpl_toolkits/axes_grid1/inset_locator.py b/lib/mpl_toolkits/axes_grid1/inset_locator.py
@@ -90,7 +90,6 @@ def __call__(self, ax, renderer):
 class AnchoredSizeLocator(AnchoredLocatorBase):
     def __init__(self, bbox_to_anchor, x_size, y_size, loc,
                  borderpad=0.5, bbox_transform=None):
-
         super().__init__(
             bbox_to_anchor, None, loc,
             borderpad=borderpad, bbox_transform=bbox_transform
@@ -105,24 +104,23 @@ def get_extent(self, renderer):
         dpi = renderer.points_to_pixels(72.)
 
         r, a = self.x_size.get_size(renderer)
-        width = w*r + a*dpi
+        width = w * r + a * dpi
 
         r, a = self.y_size.get_size(renderer)
-        height = h*r + a*dpi
+        height = h * r + a * dpi
         xd, yd = 0, 0
 
         fontsize = renderer.points_to_pixels(self.prop.get_size_in_points())
         pad = self.pad * fontsize
 
-        return width+2*pad, height+2*pad, xd+pad, yd+pad
+        return width + 2 * pad, height + 2 * pad, xd + pad, yd + pad
 
 
 class AnchoredZoomLocator(AnchoredLocatorBase):
     def __init__(self, parent_axes, zoom, loc,
                  borderpad=0.5,
                  bbox_to_anchor=None,
                  bbox_transform=None):
-
         self.parent_axes = parent_axes
         self.zoom = zoom
 
@@ -141,7 +139,7 @@ def get_extent(self, renderer):
         fontsize = renderer.points_to_pixels(self.prop.get_size_in_points())
         pad = self.pad * fontsize
 
-        return abs(w*self.zoom)+2*pad, abs(h*self.zoom)+2*pad, pad, pad
+        return abs(w * self.zoom) + 2 * pad, abs(h * self.zoom) + 2 * pad, pad, pad
 
 
 class BboxPatch(Patch):
@@ -184,6 +182,7 @@ def get_path(self):
                  Path.CLOSEPOLY]
 
         return Path(verts, codes)
+
     get_path.__doc__ = Patch.get_path.__doc__
 
 
@@ -318,6 +317,7 @@ def __init__(self, bbox1, bbox2, loc1, loc2=None, **kwargs):
     def get_path(self):
         return self.connect_bbox(self.bbox1, self.bbox2,
                                  self.loc1, self.loc2)
+
     get_path.__doc__ = Patch.get_path.__doc__
 
 
@@ -373,6 +373,7 @@ def get_path(self):
                        list(path2.vertices) +
                        [path1.vertices[0]])
         return Path(path_merged)
+
     get_path.__doc__ = BboxConnector.get_path.__doc__
 
 
@@ -453,6 +454,9 @@ def inset_axes(parent_axes, width, height, loc=1,
     if bbox_to_anchor is None:
         bbox_to_anchor = parent_axes.bbox
 
+    if bbox_transform is None:
+        bbox_transform = parent_axes.transAxes
+
     axes_locator = AnchoredSizeLocator(bbox_to_anchor,
                                        width, height,
                                        loc=loc,

diff --git a/lib/mpl_toolkits/tests/baseline_images/test_axes_grid1/inset_axes.png b/lib/mpl_toolkits/tests/baseline_images/test_axes_grid1/inset_axes.png
diff --git a/lib/mpl_toolkits/tests/test_axes_grid1.py b/lib/mpl_toolkits/tests/test_axes_grid1.py
@@ -9,7 +9,11 @@
 from mpl_toolkits.axes_grid1 import host_subplot
 from mpl_toolkits.axes_grid1 import make_axes_locatable
 from mpl_toolkits.axes_grid1 import AxesGrid
-from mpl_toolkits.axes_grid1.inset_locator import zoomed_inset_axes, mark_inset
+from mpl_toolkits.axes_grid1.inset_locator import (
+    zoomed_inset_axes,
+    mark_inset,
+    inset_axes
+)
 from mpl_toolkits.axes_grid1.anchored_artists import AnchoredSizeBar
 
 from matplotlib.colors import LogNorm
@@ -155,6 +159,73 @@ def get_demo_image():
     ax.add_artist(asb)
 
 
+@image_comparison(
+    baseline_images=['inset_axes'], style='default', extensions=['png'],
+    remove_text=True)
+def test_inset_axes():
+    def get_demo_image():
+        from matplotlib.cbook import get_sample_data
+        import numpy as np
+        f = get_sample_data("axes_grid/bivariate_normal.npy", asfileobj=False)
+        z = np.load(f)
+        # z is a numpy array of 15x15
+        return z, (-3, 4, -4, 3)
+
+    fig, ax = plt.subplots(figsize=[5, 4])
+
+    # prepare the demo image
+    Z, extent = get_demo_image()
+    Z2 = np.zeros([150, 150], dtype="d")
+    ny, nx = Z.shape
+    Z2[30:30 + ny, 30:30 + nx] = Z
+
+    # extent = [-3, 4, -4, 3]
+    ax.imshow(Z2, extent=extent, interpolation="nearest",
+              origin="lower")
+
+    # creating our inset axes without a bbox_transform parameter
+    axins = inset_axes(ax, width=1., height=1., bbox_to_anchor=(1, 1))
+
+    axins.imshow(Z2, extent=extent, interpolation="nearest",
+                 origin="lower")
+    axins.yaxis.get_major_locator().set_params(nbins=7)
+    axins.xaxis.get_major_locator().set_params(nbins=7)
+    # sub region of the original image
+    x1, x2, y1, y2 = -1.5, -0.9, -2.5, -1.9
+    axins.set_xlim(x1, x2)
+    axins.set_ylim(y1, y2)
+
+    plt.xticks(visible=False)
+    plt.yticks(visible=False)
+
+    # draw a bbox of the region of the inset axes in the parent axes and
+    # connecting lines between the bbox and the inset axes area
+    mark_inset(ax, axins, loc1=2, loc2=4, fc="none", ec="0.5")
+
+    asb = AnchoredSizeBar(ax.transData,
+                          0.5,
+                          '0.5',
+                          loc=8,
+                          pad=0.1, borderpad=0.5, sep=5,
+                          frameon=False)
+    ax.add_artist(asb)
+
+
+def test_inset_axes_without_transform_should_use_parent_axes():
+    # creating our figure
+    fig = plt.figure(dpi=150)
+
+    # gca method gets current axes of the figure
+    ax = plt.gca()
+    ax.plot([0.0, 0.25, 0.50, 1.0], [0.1, 0.2, 0.4, 0.9], color='b')
+
+    # creating our inset_axes. without a bbox_transform parameter
+    ax_ins = inset_axes(ax, width=1., height=1., bbox_to_anchor=(1, 1))
+    ax_ins.plot([0.0, 0.25, 0.50, 1.0], [0.9, 0.4, 0.2, 0.1], color='r')
+
+    assert ax.transAxes == ax_ins.transAxes
+
+
 @image_comparison(baseline_images=['zoomed_axes',
                                    'inverted_zoomed_axes'],
                   extensions=['png'])