mathtext now supports \text

oscargus · oscargus · commit f55733ed4537 · 2023-03-30T10:37:29.000+02:00
diff --git a/doc/users/next_whats_new/mathtext_supports_text.rst b/doc/users/next_whats_new/mathtext_supports_text.rst
@@ -0,0 +1,12 @@
+``mathtext`` now supports ``\text``
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+``\text`` can be used to obtain upright text within an equation.
+
+.. plot::
+    :include-source: true
+    :alt: Illustration of the newly added \text command, showing that it renders as normal text, including spaces, despite being part of an equation. Also show that a dash is not rendered as a minus when part of a \text command.
+
+import matplotlib.pyplot as plt
+plt.text(0.1, 0.5, r"$a = \sin(\phi) \text{ such that } \phi = \frac{x}{y}$")
+plt.text(0.1, 0.3, r"$\text{dashes (-) are retained}$")
diff --git a/galleries/users_explain/text/mathtext.py b/galleries/users_explain/text/mathtext.py
@@ -272,6 +272,10 @@
 that far fewer symbols will be available, but it can be useful to make math
 expressions blend well with other text in the plot.
 
+For compatibility with popular packages, ``\text{...}`` is available and uses the
+``\mathrm{...}`` font, but otherwise retains spaces and renders - as a dash
+(not minus).
+
 Custom fonts
 ~~~~~~~~~~~~
 mathtext also provides a way to use custom fonts for math.  This method is
diff --git a/lib/matplotlib/_mathtext.py b/lib/matplotlib/_mathtext.py
@@ -1857,6 +1857,7 @@ def csnames(group, names):
         p.optional_group   = Forward()
         p.sqrt             = Forward()
         p.subsuper         = Forward()
+        p.text             = Forward()
         p.token            = Forward()
         p.underset         = Forward()
 
@@ -1907,6 +1908,8 @@ def csnames(group, names):
             r"\underset",
             p.optional_group("annotation") + p.optional_group("body"))
 
+        p.text <<= cmd(r"\text", QuotedString('{', '\\', endQuoteChar="}"))
+
         p.placeable     <<= (
             p.accent     # Must be before symbol as all accents are symbols
             | p.symbol   # Must be second to catch all named symbols and single
@@ -1922,6 +1925,7 @@ def csnames(group, names):
             | p.underset
             | p.sqrt
             | p.overline
+            | p.text
         )
 
         p.simple        <<= (
@@ -2022,6 +2026,14 @@ def non_math(self, s, loc, toks):
 
     float_literal = staticmethod(pyparsing_common.convertToFloat)
 
+    def text(self, s, loc, toks):
+        self.push_state()
+        state = self.get_state()
+        state.font = 'rm'
+        hlist = Hlist([Char(c, state) for c in toks[1]])
+        self.pop_state()
+        return [hlist]
+
     def _make_space(self, percentage):
         # In TeX, an em (the unit usually used to measure horizontal lengths)
         # is not the width of the character 'm'; it is the same in different
diff --git a/lib/matplotlib/tests/baseline_images/test_mathtext/mathtext1_dejavusans_04.png b/lib/matplotlib/tests/baseline_images/test_mathtext/mathtext1_dejavusans_04.png
diff --git a/lib/matplotlib/tests/test_mathtext.py b/lib/matplotlib/tests/test_mathtext.py
@@ -130,6 +130,8 @@
     r'$x \overset{f}{\rightarrow} \overset{f}{x} \underset{xx}{ff} \overset{xx}{ff} \underset{f}{x} \underset{f}{\leftarrow} x$',  # github issue #18241
     r'$\sum x\quad\sum^nx\quad\sum_nx\quad\sum_n^nx\quad\prod x\quad\prod^nx\quad\prod_nx\quad\prod_n^nx$',  # GitHub issue 18085
     r'$1.$ $2.$ $19680801.$ $a.$ $b.$ $mpl.$',
+    r'$\text{text}_{\text{sub}}^{\text{sup}} + \text{\$foo\$} + \frac{\text{num}}{\mathbf{\text{den}}}\text{with space, curly brackets \{\}, and dash -}$',
+
 ]
 
 digits = "0123456789"

Original file line number	Diff line number	Diff line change
`@@ -130,6 +130,8 @@`
`130`	`130`	`r'$x \overset{f}{\rightarrow} \overset{f}{x} \underset{xx}{ff} \overset{xx}{ff} \underset{f}{x} \underset{f}{\leftarrow} x$', # github issue #18241`
`131`	`131`	`r'$\sum x\quad\sum^nx\quad\sum_nx\quad\sum_n^nx\quad\prod x\quad\prod^nx\quad\prod_nx\quad\prod_n^nx$', # GitHub issue 18085`
`132`	`132`	`r'$1.$ $2.$ $19680801.$ $a.$ $b.$ $mpl.$',`
	`133`	`+ r'$\text{text}_{\text{sub}}^{\text{sup}} + \text{\$foo\$} + \frac{\text{num}}{\mathbf{\text{den}}}\text{with space, curly brackets \{\}, and dash -}$',`
	`134`	`+`
`133`	`135`	`]`
`134`	`136`
`135`	`137`	`digits = "0123456789"`