Add a tutorial for typesetting non-ASCII characters (#3389)

Co-authored-by: Yvonne Fröhlich <[email protected]>

examples/tutorials/advanced/non_ascii_text.py

@@ -0,0 +1,77 @@
+# ruff: noqa: RUF001,RUF003
+"""
+Typesetting non-ASCII text
+--------------------------
+
+In addition to ASCII printable characters, sometimes you may also want to typeset
+non-ASCII characters on the plot, such as Greek letters, mathematical symbols, or
+special characters.
+
+Due to the limitations of the underlying PostScript language, PyGMT doesn't support
+all characters in the Unicode standard. Instead, PyGMT supports a limited set of
+characters in the "Adobe Symbol", "Adobe ZapfDingbats", "Adobe ISOLatin1+", and
+"ISO-8859-*x*" (*x* can be 1-11, 13-16) encodings. Refer to :doc:`/techref/encodings`
+for the complete list of supported characters.
+
+In PyGMT, the supported (ASCII and non-ASCII) characters can be directly used in the
+``text`` parameter of the :meth:`pygmt.Figure.text` method for typesetting text strings.
+They can also be used in the arguments of other plotting functions (e.g., in the
+``frame`` parameter to set the labels or title).
+
+In this example, we demonstrate how to typeset non-ASCII characters in PyGMT.
+"""
+
+# %%
+import pygmt
+
+fig = pygmt.Figure()
+fig.basemap(
+    region=[0, 5, 0, 6],
+    projection="X14c/7c",
+    frame=["xaf+lDistance (°)", "yaf+lValue (‰)", "WSen+tTitle: α² ± β²"],
+)
+
+fig.text(
+    x=[0.2, 0.2, 0.2, 0.2, 0.2],
+    y=[5, 4, 3, 2, 1],
+    text=["ASCII:", "ISOLatin1+:", "Symbol:", "ZapfDingbats:", "Mixed:"],
+    font="20p,Helvetica-Bold,red",
+    justify="LM",
+)
+fig.text(
+    x=[2, 2, 2, 2, 2],
+    y=[5, 4, 3, 2, 1],
+    text=[
+        "ABCDE12345!#$:;<=>?",  # ASCII only
+        "±°ÀÁÂÃÄÅÈÌÒÙàèìòù",  # Non-ASCII characters from Adobe ISOLatin1+
+        "αβγδεζηθ⊗⊕∅⊃⊇⊄⊂⊆",  # Non-ASCII characters from Adobe Symbol
+        "✈♥♦♣♠❛❜❝❞❨❩❪❫❬❭❮❯→↔",  # Non-ASCII characters from Adobe ZapfDingbats
+        "ABCD αβγδ ①②③ ➊➋➌",  # Mix characters from ISOLatin1+, Symbol and ZapfDingbats
+    ],
+    font="18p,Helvetica",
+    justify="LM",
+)
+
+fig.show()
+
+# %%
+# Here are some important tips when using non-ASCII characters:
+#
+# - **Similar-looking characters**: Be cautious when using characters that appear
+#   visually similar but are distinct. For example, ``Ω`` (OHM SIGN) and ``Ω`` (GREEK
+#   CAPITAL LETTER OMEGA) may look alike, but PyGMT only supports the latter. Using the
+#   incorrect character can lead to unexpected results. To avoid this, it's recommended
+#   to copy and paste characters from the :doc:`/techref/encodings` documentation.
+# - **Mix characters from different encodings**: As shown in the example above, you can
+#   mix characters from different encodings in the same text string. However, due to the
+#   limitations of the underlying PostScript language, you cannot mix characters from
+#   the "Adobe ISOLatin1+" and "ISO-8859-*x*" encodings in the same text string. For
+#   example, you cannot mix characters from "Adobe ISOLatin1+" and "ISO-8859-2". If
+#   you need to use characters from different encodings, you can use them in different
+#   PyGMT function/method calls.
+# - **Non-ASCII characters in text files**: Non-ASCII characters are not supported if
+#   you have them in a text file and pass it to :meth:`pygmt.Figure.text`. In this case,
+#   you may want to load the text file into :class:`pandas.DataFrame` and then pass it
+#   to the ``text`` parameter.
+
+# sphinx_gallery_thumbnail_number = 1