Merge pull request #12847 from pharshalp/engformatter_tex_fix

jklymak · web-flow · commit f8b425dfbe20 · 2018-11-20T16:16:16.000-08:00
correctly format ticklabels when EngFormatter is used with usetex = True
diff --git a/lib/matplotlib/tests/test_usetex.py b/lib/matplotlib/tests/test_usetex.py
@@ -5,6 +5,7 @@
 import matplotlib
 from matplotlib.testing.decorators import image_comparison
 import matplotlib.pyplot as plt
+from matplotlib.ticker import EngFormatter
 
 
 with warnings.catch_warnings():
@@ -31,3 +32,18 @@ def test_usetex():
             fontsize=24)
     ax.set_xticks([])
     ax.set_yticks([])
+
+
+@needs_usetex
+def test_usetex_engformatter():
+    matplotlib.rcParams['text.usetex'] = True
+    fig, ax = plt.subplots()
+    ax.plot([0, 500, 1000], [0, 500, 1000])
+    ax.set_xticks([0, 500, 1000])
+    formatter = EngFormatter()
+    ax.xaxis.set_major_formatter(formatter)
+    fig.canvas.draw()
+    x_tick_label_text = [label.get_text() for label in ax.get_xticklabels()]
+    # Checking if the dollar `$` signs have been inserted around numbers
+    # in tick label text.
+    assert x_tick_label_text == ['$0$', '$500$', '$1$ k']
diff --git a/lib/matplotlib/ticker.py b/lib/matplotlib/ticker.py
@@ -1283,9 +1283,12 @@ def format_eng(self, num):
             pow10 += 3
 
         prefix = self.ENG_PREFIXES[int(pow10)]
-
-        formatted = "{mant:{fmt}}{sep}{prefix}".format(
-            mant=mant, sep=self.sep, prefix=prefix, fmt=fmt)
+        if rcParams['text.usetex']:
+            formatted = "${mant:{fmt}}${sep}{prefix}".format(
+                mant=mant, sep=self.sep, prefix=prefix, fmt=fmt)
+        else:
+            formatted = "{mant:{fmt}}{sep}{prefix}".format(
+                mant=mant, sep=self.sep, prefix=prefix, fmt=fmt)
 
         return formatted
 
