BUG: fixed weird case where boxplot whiskers went inside box

phobson · pelson · commit c7278d264b53 · 2013-05-14T11:04:22.000+01:00
diff --git a/doc/users/whats_new.rst b/doc/users/whats_new.rst
@@ -84,6 +84,12 @@ using Inkscape for example, while preserving their intended position. For
 `svg` please note that you'll have to disable the default text-to-path
 conversion (`mpl.rc('svg', fonttype='none')`).
 
+More robust boxplots
+--------------------
+Paul Hobson provided a fix to the :func:`~matplotlib.pyplot.boxplot`
+method that prevent whiskers from being drawn inside the box for 
+oddly distributed data sets.
+
 Triangular grid interpolation
 -----------------------------
 Geoffroy Billotey and Ian Thomas added classes to perform interpolation within
diff --git a/lib/matplotlib/axes.py b/lib/matplotlib/axes.py
@@ -6027,17 +6027,19 @@ def computeConfInterval(data, med, iq, bootstrap):
             iq = q3 - q1
             hi_val = q3 + whis * iq
             wisk_hi = np.compress(d <= hi_val, d)
-            if len(wisk_hi) == 0:
+            if len(wisk_hi) == 0 or np.max(wisk_hi) < q3:
                 wisk_hi = q3
             else:
                 wisk_hi = max(wisk_hi)
+            
             # get low extreme
             lo_val = q1 - whis * iq
             wisk_lo = np.compress(d >= lo_val, d)
-            if len(wisk_lo) == 0:
+            if len(wisk_lo) == 0 or np.min(wisk_lo) > q1:
                 wisk_lo = q1
             else:
                 wisk_lo = min(wisk_lo)
+            
             # get fliers - if we are showing them
             flier_hi = []
             flier_lo = []
diff --git a/lib/matplotlib/tests/baseline_images/test_axes/boxplot_no_inverted_whisker.png b/lib/matplotlib/tests/baseline_images/test_axes/boxplot_no_inverted_whisker.png
diff --git a/lib/matplotlib/tests/test_axes.py b/lib/matplotlib/tests/test_axes.py
@@ -964,6 +964,18 @@ def test_boxplot():
                conf_intervals=[None, (-1.0, 3.5)], notch=1)
     ax.set_ylim((-30, 30))
 
+@image_comparison(baseline_images=['boxplot_no_inverted_whisker'],
+                  remove_text=True, extensions=['png'],
+                  savefig_kwarg={'dpi': 40})
+def test_boxplot_no_weird_whisker():
+    x = np.array([3, 9000, 150, 88, 350, 200000, 1400, 960], 
+                dtype=np.float64)
+    ax1 = plt.axes()
+    ax1.boxplot(x)
+    ax1.set_yscale('log')
+    ax1.yaxis.grid(False, which='minor')
+    ax1.xaxis.grid(False)
+
 @image_comparison(baseline_images=['errorbar_basic',
                                    'errorbar_mixed'])
 def test_errorbar():
