TST: hard-code nbins

tacaswell · tacaswell · commit 71e0c999ce98 · 2016-01-24T14:45:45.000-05:00
Do not let the ticks in the inset adjust based on spacing of text which
is not visible.

The issue with the inset locator seems to be that as previously
implemented the axis's estimate of how many ticks it should have was
computed once and then saved.

The way that the inset axes works (if you step through this line at a
time) is that the figure-space size of the axes follows the x/y limits
at a fixed ratio to the screen-space of the same range in the main
axes. Thus, when the inset axes is created it is 'big' in that it has
limits of [0, 1] at 6x zoom -&gt; about half the size of the host axes and
so it concludes that it needs a whole bunch of ticks and remembers that.

One of the changes in this PR makes it so that the number of ticks is
recomputed every time, thus many fewer ticks are used when the axes is
small (even though the text is all turned off).
diff --git a/lib/mpl_toolkits/tests/test_axes_grid1.py b/lib/mpl_toolkits/tests/test_axes_grid1.py
@@ -134,7 +134,8 @@ def get_demo_image():
     axins = zoomed_inset_axes(ax, 6, loc=1)  # zoom = 6
     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)
