Syntax highlighting of numeric literals with the listings package

Question

I'm working on a document that contains a lot of python code snippets, many of which have numeric literals in them. For example, something like:

var_a = 3
var_b = 20000
var_c = 1.75e12
var_d = 0.1415

would be common to see in this document. Notice that StackExchange's syntax highlighting renders the numeric values in orange. I'm trying to get listings to reproduce this behavior. I have a style declaration which looks something like:

\lstdefinestyle{mystyle}{
    language=python,
    alsoletter={1234567890},
    emph={1,2,3,4,5,6,7,8,9,0},
    emphstyle=\color{orange}
}

This seems to almost work. I correctly get single-digit numbers highlighted in orange, but multi-digit numbers are not (and of course neither are floating point numbers or numbers in scientific notation). So in my example snippet above, only the first line would be correctly highlighted.

Is it possible to get listings to highlight numbers in a way that behaves more as expected? I would even be happy if it's possible to just get this to work with integers with more than one digit if floats and scientific notation aren't possible.

Some solutions and further pointers can be found at https://tex.stackexchange.com/questions/217505/listings-color-numbers-only-out-of-keywords, https://tex.stackexchange.com/questions/569914/listings-consistently-colouring-numbers, https://tex.stackexchange.com/questions/494451/the-listings-package-highlights-e3-in-20e3-as-identifier. These other answers may not be exactly what you need so I didn't put them as duplicate, but maybe you can extract a useful solution out of it. In any case using minted instead of listings would solve the problem. — Marijn, Apr 30 '22 at 19:15
@Marijn minted looks nice, although just looking through the docs I don't think I can quite just drop it in place and go with my document, I would need to tweak a bunch of things first. It may be end up being the best long-term solution anyway though. — realityChemist, Apr 30 '22 at 20:13

Simon Dispa · Accepted Answer · 2022-04-30T20:49:42.643

Try this code. Its a very simplified solution. See the links mentioned in the comments and also Changing the color of numbers and special words for more comprehensive solutions.

\documentclass{article}
\usepackage{listings}
\usepackage{xcolor}
\renewcommand{\lstlistingname}{Phyton code}
\lstdefinestyle{mystyle}{
    language=Python,

    captionpos=b,

}
\lstset{style=mystyle}
\newcommand\digitstyle{\textcolor{orange}}
    {0}{{{\digitstyle0}}}1
    {1}{{{\digitstyle1}}}1
    {2}{{{\digitstyle2}}}1
    {3}{{{\digitstyle3}}}1
    {4}{{{\digitstyle4}}}1
    {5}{{{\digitstyle5}}}1
    {6}{{{\digitstyle6}}}1
    {7}{{{\digitstyle7}}}1
    {8}{{{\digitstyle8}}}1
    {9}{{{\digitstyle9}}}1
    {.}{{{\digitstyle.}}}1
}
\begin{document}
\begin{lstlisting}[language=Python, caption=Highlighting  numeric literals.]    
    var_a = 3
    var_b = 20000
    var_c = 1.75e12
    var_d = 0.1415      
\end{lstlisting}    


\end{document}

This is a good, relatively straightforward solution. It doesn't highlight the decimal points or magnitude markers, but I'm going to see if I can get that working based on some of the other answers linked in the comments. — realityChemist, Apr 30 '22 at 20:07
@realityChemist I added the decimal point. If you want an answer to highlight more Python elements, it would be better to ask another question for the benefit of other readers. — Simon Dispa, Apr 30 '22 at 20:30

Syntax highlighting of numeric literals with the listings package

1 Answers1