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<!DOCTYPE html>

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<title>Fonts in Matplotlib — Matplotlib 3.6.3 documentation</title>

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<h1>Fonts in Matplotlib<a class="headerlink" href="#fonts-in-matplotlib" title="Permalink to this heading">#</a></h1>

<p>Matplotlib needs fonts to work with its text engine, some of which are shipped

alongside the installation. The default font is <a class="reference external" href="https://dejavu-fonts.github.io">DejaVu Sans</a> which covers most European writing systems.

However, users can configure the default fonts, and provide their own custom

fonts. See <a class="reference internal" href="../../tutorials/text/text_props.html"><span class="doc">Customizing text properties</span></a> for

details and <a class="reference internal" href="../../tutorials/text/text_props.html#font-nonlatin"><span class="std std-ref">Text with non-latin glyphs</span></a> in particular for glyphs not supported by

DejaVu Sans.</p>

<p>Matplotlib also provides an option to offload text rendering to a TeX engine

(<code class="docutils literal notranslate"><span class="pre">usetex=True</span></code>), see <a class="reference internal" href="../../tutorials/text/usetex.html"><span class="doc">Text rendering with LaTeX</span></a>.</p>

<h2>Fonts in PDF and PostScript<a class="headerlink" href="#fonts-in-pdf-and-postscript" title="Permalink to this heading">#</a></h2>

<p>Fonts have a long (and sometimes incompatible) history in computing, leading to

different platforms supporting different types of fonts. In practice,

Matplotlib supports three font specifications (in addition to pdf 'core fonts',

which are explained later in the guide):</p>

<caption><span class="caption-text">Type of Fonts</span><a class="headerlink" href="#id2" title="Permalink to this table">#</a></caption>

<thead>

<th class="head"><p>TrueType (PDF)</p></th>

</tr>

</thead>

<tbody>

<tr class="row-even"><td><p>One of the oldest types, introduced by Adobe</p></td>

<td><p>Similar to Type 1 in terms of introduction</p></td>

<td><p>Newer than previous types, used commonly today, introduced by Apple</p></td>

</tr>

<tr class="row-odd"><td><p>Restricted subset of PostScript, charstrings are in bytecode</p></td>

<td><p>Full PostScript language, allows embedding arbitrary code

(in theory, even render fractals when rasterizing!)</p></td>

<td><p>Include a virtual machine that can execute code!</p></td>

</tr>

<tr class="row-even"><td><p>These fonts support font hinting</p></td>

<td><p>Do not support font hinting</p></td>

<td><p>Hinting supported (virtual machine processes the "hints")</p></td>

</tr>

<tr class="row-odd"><td><p>Non-subsetted through Matplotlib</p></td>

<td><p>Subsetted via external module ttconv</p></td>

<td><p>Subsetted via external module <a class="reference external" href="https://github.com/fonttools/fonttools">fontTools</a></p></td>

</tr>

</tbody>

</table>

<p>Adobe <a class="reference external" href="https://helpx.adobe.com/fonts/kb/postscript-type-1-fonts-end-of-support.html">disabled</a> support for authoring with Type 1 fonts in January 2023.</p>

</div>

<p>Other font specifications which Matplotlib supports:</p>

<li><p>Type 42 fonts (PS):</p>

<ul>

<li><p>PostScript wrapper around TrueType fonts</p></li>

<li><p>42 is the <a class="reference external" href="https://en.wikipedia.org/wiki/Answer_to_Life,_the_Universe,_and_Everything">Answer to Life, the Universe, and Everything!</a></p></li>

<li><p>Matplotlib uses the external library <a class="reference external" href="https://github.com/fonttools/fonttools">fontTools</a>

to subset these types of fonts</p></li>

</ul>

</li>

<li><p>OpenType fonts:</p>

<ul>

<li><p>OpenType is a new standard for digital type fonts, developed jointly by

Adobe and Microsoft</p></li>

<li><p>Generally contain a much larger character set!</p></li>

<li><p>Limited support with Matplotlib</p></li>

</ul>

</li>

</ul>

<h3>Font subsetting<a class="headerlink" href="#font-subsetting" title="Permalink to this heading">#</a></h3>

<p>The PDF and PostScript formats support embedding fonts in files, allowing the

display program to correctly render the text, independent of what fonts are

installed on the viewer's computer and without the need to pre-rasterize the text.

This ensures that if the output is zoomed or resized the text does not become

pixelated. However, embedding full fonts in the file can lead to large output

files, particularly with fonts with many glyphs such as those that support CJK

(Chinese/Japanese/Korean).</p>

<p>The solution to this problem is to subset the fonts used in the document and

only embed the glyphs actually used. This gets both vector text and small

files sizes. Computing the subset of the font required and writing the new

(reduced) font are both complex problem and thus Matplotlib relies on

<a class="reference external" href="https://fonttools.readthedocs.io/en/latest/">fontTools</a> and a vendored fork

of ttconv.</p>

<p>Currently Type 3, Type 42, and TrueType fonts are subsetted. Type 1 fonts are not.</p>

</section>

<h3>Core Fonts<a class="headerlink" href="#core-fonts" title="Permalink to this heading">#</a></h3>

<p>In addition to the ability to embed fonts, as part of the <a class="reference external" href="https://en.wikipedia.org/wiki/PostScript_fonts#Core_Font_Set">PostScript</a> and <a class="reference external" href="https://docs.oracle.com/cd/E96927_01/TSG/FAQ/What%20are%20the%2014%20base%20fonts%20distributed%20with%20Acroba.html">PDF

specification</a>

there are 14 Core Fonts that compliant viewers must ensure are available. If

you restrict your document to only these fonts you do not have to embed any

font information in the document but still get vector text.</p>

<p>This is especially helpful to generate <em>really lightweight</em> documents:</p>

<div class="highlight-default notranslate"><div class="highlight"><pre><span></span><span class="c1"># trigger core fonts for PDF backend</span>

<span class="n">plt</span><span class="o">.</span><span class="n">rcParams</span><span class="p">[</span><span class="s2">"pdf.use14corefonts"</span><span class="p">]</span> <span class="o">=</span> <span class="kc">True</span>

<span class="c1"># trigger core fonts for PS backend</span>

<span class="n">plt</span><span class="o">.</span><span class="n">rcParams</span><span class="p">[</span><span class="s2">"ps.useafm"</span><span class="p">]</span> <span class="o">=</span> <span class="kc">True</span>

<span class="n">chars</span> <span class="o">=</span> <span class="s2">"AFM ftw!"</span>

<span class="n">fig</span><span class="p">,</span> <span class="n">ax</span> <span class="o">=</span> <span class="n">plt</span><span class="o">.</span><span class="n">subplots</span><span class="p">()</span>

<span class="n">ax</span><span class="o">.</span><span class="n">text</span><span class="p">(</span><span class="mf">0.5</span><span class="p">,</span> <span class="mf">0.5</span><span class="p">,</span> <span class="n">chars</span><span class="p">)</span>

<span class="n">fig</span><span class="o">.</span><span class="n">savefig</span><span class="p">(</span><span class="s2">"AFM_PDF.pdf"</span><span class="p">,</span> <span class="nb">format</span><span class="o">=</span><span class="s2">"pdf"</span><span class="p">)</span>

<span class="n">fig</span><span class="o">.</span><span class="n">savefig</span><span class="p">(</span><span class="s2">"AFM_PS.ps"</span><span class="p">,</span> <span class="nb">format</span><span class="o">=</span><span class="s2">"ps)</span>

</pre></div>

</div>

</section>

<h2>Fonts in SVG<a class="headerlink" href="#fonts-in-svg" title="Permalink to this heading">#</a></h2>

<p>Text can output to SVG in two ways controlled by <code class="docutils literal notranslate"><a class="reference internal" href="../../tutorials/introductory/customizing.html?highlight=svg.fonttype#matplotlibrc-sample"><span class="std std-ref"><span class="pre">rcParams["svg.fonttype"]</span></span></a></code> (default: <code class="docutils literal notranslate"><span class="pre">'path'</span></code>):</p>

<li><p>as string in the SVG with font styling on the element (<code class="docutils literal notranslate"><span class="pre">'none'</span></code>)</p></li>

</ul>

<p>When saving via <code class="docutils literal notranslate"><span class="pre">'path'</span></code> Matplotlib will compute the path of the glyphs used

as vector paths and write those to the output. The advantage of doing so is

that the SVG will look the same on all computers independent of what fonts are

installed. However the text will not be editable after the fact.

In contrast, saving with <code class="docutils literal notranslate"><span class="pre">'none'</span></code> will result in smaller files and the

text will appear directly in the markup. However, the appearance may vary

based on the SVG viewer and what fonts are available.</p>

</section>

<h2>Fonts in Agg<a class="headerlink" href="#fonts-in-agg" title="Permalink to this heading">#</a></h2>

<p>To output text to raster formats via Agg, Matplotlib relies on <a class="reference external" href="https://www.freetype.org/">FreeType</a>. Because the exact rendering of the glyphs

changes between FreeType versions we pin to a specific version for our image

comparison tests.</p>

</section>

<h2>How Matplotlib selects fonts<a class="headerlink" href="#how-matplotlib-selects-fonts" title="Permalink to this heading">#</a></h2>

<p>Internally, using a font in Matplotlib is a three step process:</p>

<li><p>a <a class="reference internal" href="../../api/font_manager_api.html#matplotlib.font_manager.FontProperties" title="matplotlib.font_manager.FontProperties"><code class="xref py py-obj docutils literal notranslate"><span class="pre">FontProperties</span></code></a> object is created (explicitly or implicitly)</p></li>

<li><p>based on the <a class="reference internal" href="../../api/font_manager_api.html#matplotlib.font_manager.FontProperties" title="matplotlib.font_manager.FontProperties"><code class="xref py py-obj docutils literal notranslate"><span class="pre">FontProperties</span></code></a> object the methods on <a class="reference internal" href="../../api/font_manager_api.html#matplotlib.font_manager.FontManager" title="matplotlib.font_manager.FontManager"><code class="xref py py-obj docutils literal notranslate"><span class="pre">FontManager</span></code></a> are used

to select the closest "best" font Matplotlib is aware of (except for

<li><p>the Python proxy for the font object is used by the backend code to render

the text -- the exact details depend on the backend via <a class="reference internal" href="../../api/font_manager_api.html#matplotlib.font_manager.get_font" title="matplotlib.font_manager.get_font"><code class="xref py py-obj docutils literal notranslate"><span class="pre">font_manager.get_font</span></code></a>.</p></li>

</ol>

<p>The algorithm to select the "best" font is a modified version of the algorithm

specified by the <a class="reference external" href="http://www.w3.org/TR/1998/REC-CSS2-19980512/">CSS1 Specifications</a> which is used by web browsers.

This algorithm takes into account the font family name (e.g. "Arial", "Noto

Sans CJK", "Hack", ...), the size, style, and weight. In addition to family

names that map directly to fonts there are five "generic font family names"

(serif, monospace, fantasy, cursive, and sans-serif) that will internally be

mapped to any one of a set of fonts.</p>

<p>Currently the public API for doing step 2 is <a class="reference internal" href="../../api/font_manager_api.html#matplotlib.font_manager.FontManager.findfont" title="matplotlib.font_manager.FontManager.findfont"><code class="xref py py-obj docutils literal notranslate"><span class="pre">FontManager.findfont</span></code></a> (and that

method on the global <a class="reference internal" href="../../api/font_manager_api.html#matplotlib.font_manager.FontManager" title="matplotlib.font_manager.FontManager"><code class="xref py py-obj docutils literal notranslate"><span class="pre">FontManager</span></code></a> instance is aliased at the module level as

<a class="reference internal" href="../../api/font_manager_api.html#matplotlib.font_manager.findfont" title="matplotlib.font_manager.findfont"><code class="xref py py-obj docutils literal notranslate"><span class="pre">font_manager.findfont</span></code></a>), which will only find a single font and return the absolute

path to the font on the filesystem.</p>

</section>

<h2>Font fallback<a class="headerlink" href="#font-fallback" title="Permalink to this heading">#</a></h2>

<p>There is no font that covers the entire Unicode space thus it is possible for the

users to require a mix of glyphs that can not be satisfied from a single font.

While it has been possible to use multiple fonts within a Figure, on distinct

<a class="reference internal" href="../../api/text_api.html#matplotlib.text.Text" title="matplotlib.text.Text"><code class="xref py py-obj docutils literal notranslate"><span class="pre">Text</span></code></a> instances, it was not previous possible to use multiple fonts in the

same <a class="reference internal" href="../../api/text_api.html#matplotlib.text.Text" title="matplotlib.text.Text"><code class="xref py py-obj docutils literal notranslate"><span class="pre">Text</span></code></a> instance (as a web browser does). As of Matplotlib 3.6 the Agg,

SVG, PDF, and PS backends will "fallback" through multiple fonts in a single

<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="n">fig</span><span class="p">,</span> <span class="n">ax</span> <span class="o">=</span> <span class="n">plt</span><span class="o">.</span><span class="n">subplots</span><span class="p">()</span>

<span class="mf">.5</span><span class="p">,</span> <span class="mf">.5</span><span class="p">,</span> <span class="s2">"There are 几个汉字 in between!"</span><span class="p">,</span>

<span class="n">family</span><span class="o">=</span><span class="p">[</span><span class="s1">'DejaVu Sans'</span><span class="p">,</span> <span class="s1">'WenQuanYi Zen Hei'</span><span class="p">],</span>

<span class="n">ha</span><span class="o">=</span><span class="s1">'center'</span>

</pre></div>

</div>

<p>(<a class="reference external" href="../../users/explain/fonts-1.py">Source code</a>, <a class="reference external" href="../../users/explain/fonts-1.png">png</a>)</p>

<p><span class="caption-text">The string "There are 几个汉字 in between!" rendered with 2 fonts.</span><a class="headerlink" href="#id3" title="Permalink to this image">#</a></p>

</figcaption>

</figure>

<p>Internally this is implemented by setting The "font family" on

<a class="reference internal" href="../../api/font_manager_api.html#matplotlib.font_manager.FontProperties" title="matplotlib.font_manager.FontProperties"><code class="xref py py-obj docutils literal notranslate"><span class="pre">FontProperties</span></code></a> objects to a list of font families. A (currently)

private API extracts a list of paths to all of the fonts found and then

constructs a single <a class="reference internal" href="../../api/ft2font.html#matplotlib.ft2font.FT2Font" title="matplotlib.ft2font.FT2Font"><code class="xref py py-obj docutils literal notranslate"><span class="pre">ft2font.FT2Font</span></code></a> object that is aware of all of the fonts.

Each glyph of the string is rendered using the first font in the list that

contains that glyph.</p>

<p>A majority of this work was done by Aitik Gupta supported by Google Summer of

Code 2021.</p>

</section>

</article>

</div>

<i class="fa-solid fa-list"></i> On this page

</div>

Fonts in PDF and PostScript

</a>

Font subsetting

</a>

</li>

Core Fonts

</a>

</li>

</ul>

</li>

Fonts in SVG

</a>

</li>

Fonts in Agg

</a>

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How Matplotlib selects fonts

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