matplotlib · QuLogic · Jul 26, 2017 · Feb 26, 2017 · Feb 26, 2017 · Feb 26, 2017
diff --git a/examples/text_labels_and_annotations/dfrac_demo.py b/examples/text_labels_and_annotations/dfrac_demo.py
@@ -0,0 +1,28 @@
+"""
+=======================================
+The difference between \dfrac and \frac
+=======================================
+
+In this example, the differences between the \dfrac and \frac TeX macros are
+illustrated; in particular, the difference between display style and text style
+fractions when using Mathtex.
+
+.. versionadded:: 2.1
+
+.. note::
+    To use \dfrac with the LaTeX engine (text.usetex : True), you need to
+    import the amsmath package with the text.latex.preamble rc, which is
+    an unsupported feature; therefore, it is probably a better idea to just
+    use the \displaystyle option before the \frac macro to get this behavior
+    with the LaTeX engine.
+
+"""
+
+import matplotlib.pyplot as plt
+
+fig = plt.figure(figsize=(5.25, 0.75))
+fig.text(0.5, 0.3, r'\dfrac: $\dfrac{a}{b}$',
+         horizontalalignment='center', verticalalignment='center')
+fig.text(0.5, 0.7, r'\frac: $\frac{a}{b}$',
+         horizontalalignment='center', verticalalignment='center')
+plt.show()
diff --git a/lib/matplotlib/mathtext.py b/lib/matplotlib/mathtext.py
@@ -2309,6 +2309,7 @@ def __init__(self):
         p.float_literal    = Forward()
         p.font             = Forward()
         p.frac             = Forward()
+        p.dfrac            = Forward()
         p.function         = Forward()
         p.genfrac          = Forward()
         p.group            = Forward()
@@ -2397,6 +2398,11 @@ def __init__(self):
                            - ((p.required_group + p.required_group) | Error(r"Expected \frac{num}{den}"))
                          )
 
+        p.dfrac         <<= Group(
+                             Suppress(Literal(r"\dfrac"))
+                           - ((p.required_group + p.required_group) | Error(r"Expected \dfrac{num}{den}"))
+                         )
+
         p.stackrel      <<= Group(
                              Suppress(Literal(r"\stackrel"))
                            - ((p.required_group + p.required_group) | Error(r"Expected \stackrel{num}{den}"))
@@ -2449,6 +2455,7 @@ def __init__(self):
                          | p.function
                          | p.group
                          | p.frac
+                         | p.dfrac
                          | p.stackrel
                          | p.binom
                          | p.genfrac
@@ -3043,8 +3050,11 @@ def _genfrac(self, ldelim, rdelim, rule, style, num, den):
             state.font, state.fontsize, state.dpi)
 
         rule = float(rule)
-        num.shrink()
-        den.shrink()
+
+        # If style != displaystyle == 0, shrink the num and den
+        if style:
+            num.shrink()
+            den.shrink()
         cnum = HCentered([num])
         cden = HCentered([den])
         width = max(num.width, den.width)
@@ -3077,35 +3087,46 @@ def _genfrac(self, ldelim, rdelim, rule, style, num, den):
         return result
 
     def genfrac(self, s, loc, toks):
-        assert(len(toks)==1)
-        assert(len(toks[0])==6)
+        assert(len(toks) == 1)
+        assert(len(toks[0]) == 6)
 
         return self._genfrac(*tuple(toks[0]))
 
     def frac(self, s, loc, toks):
-        assert(len(toks)==1)
-        assert(len(toks[0])==2)
+        assert(len(toks) == 1)
+        assert(len(toks[0]) == 2)
+        state = self.get_state()
+
+        thickness = state.font_output.get_underline_thickness(
+            state.font, state.fontsize, state.dpi)
+        num, den = toks[0]
+
+        return self._genfrac('', '', thickness, 1, num, den)
+
+    def dfrac(self, s, loc, toks):
+        assert(len(toks) == 1)
+        assert(len(toks[0]) == 2)
         state = self.get_state()
 
         thickness = state.font_output.get_underline_thickness(
             state.font, state.fontsize, state.dpi)
         num, den = toks[0]
 
-        return self._genfrac('', '', thickness, '', num, den)
+        return self._genfrac('', '', thickness, 0, num, den)
 
     def stackrel(self, s, loc, toks):
-        assert(len(toks)==1)
-        assert(len(toks[0])==2)
+        assert(len(toks) == 1)
+        assert(len(toks[0]) == 2)
         num, den = toks[0]
 
-        return self._genfrac('', '', 0.0, '', num, den)
+        return self._genfrac('', '', 0.0, 1, num, den)
 
     def binom(self, s, loc, toks):
-        assert(len(toks)==1)
-        assert(len(toks[0])==2)
+        assert(len(toks) == 1)
+        assert(len(toks[0]) == 2)
         num, den = toks[0]
 
-        return self._genfrac('(', ')', 0.0, '', num, den)
+        return self._genfrac('(', ')', 0.0, 1, num, den)
 
     def sqrt(self, s, loc, toks):
         #~ print "sqrt", toks

diff --git a/lib/matplotlib/tests/baseline_images/test_mathtext/mathtext_stixsans_82.pdf b/lib/matplotlib/tests/baseline_images/test_mathtext/mathtext_stixsans_82.pdf
diff --git a/lib/matplotlib/tests/baseline_images/test_mathtext/mathtext_stixsans_82.png b/lib/matplotlib/tests/baseline_images/test_mathtext/mathtext_stixsans_82.png
diff --git a/lib/matplotlib/tests/baseline_images/test_mathtext/mathtext_stixsans_82.svg b/lib/matplotlib/tests/baseline_images/test_mathtext/mathtext_stixsans_82.svg
diff --git a/lib/matplotlib/tests/test_mathtext.py b/lib/matplotlib/tests/test_mathtext.py
@@ -110,6 +110,7 @@
     r'$\overline{\omega}^x \frac{1}{2}_0^x$', # github issue #5444
     r'$,$ $.$ $1{,}234{, }567{ , }890$ and $1,234,567,890$', # github issue 5799
     r'$\left(X\right)_{a}^{b}$', # github issue 7615
+    r'$\dfrac{\$100.00}{y}$', # github issue #1888
 ]
 
 digits = "0123456789"
@@ -223,6 +224,8 @@ def test_fontinfo():
         (r'$\rightF$', r'Unknown symbol: \rightF'),
         (r'$\left(\right$', r'Expected a delimiter'),
         (r'$\left($', r'Expected "\right"'),
+        (r'$\dfrac$', r'Expected \dfrac{num}{den}'),
+        (r'$\dfrac{}{}$', r'Expected \dfrac{num}{den}'),
     ],
     ids=[
         'hspace without value',
@@ -243,6 +246,8 @@ def test_fontinfo():
         'right with invalid delimiter',
         'unclosed parentheses with sizing',
         'unclosed parentheses without sizing',
+        'dfrac without parameters',
+        'dfrac with empty parameters',
     ]
 )
 def test_mathtext_exceptions(math, msg):