Latex $<Text>$ to markdown which don't support mathjax

latex_to_markdwon.md

Latex dollars to markdown which don't support mathjax

Since GitHub READEME doesn't seems to sopport math mode like $\int_0^1 cos(\theta) d\theta = 1$

We can workaround this using codecogs which is an online latex equation editor which provvides it's outpus as gifs.

The base gif url is https://latex.codecogs.com/gif.latex? which is followed by the percentage encoded query.

So i made this function to convert an equation to a Markdown image:

def convert_eq(text):
    encoded = "".join([encoding.get(c,c) for c in text])
    url = base_url + encoded
    md = "![](%s)"%url
    return md

That when called:

convert_eq("""\int_0^1 cos(\theta) d\theta = 1""")

gives:

![](https://latex.codecogs.com/gif.latex?%5Cint%5F0%5E1%20cos%28\theta%29%20d\theta%20%3D%201)

which in markdown is:

.

Generalizzation

This can be generalized to convert all the occurance of the double dollars in a file:

#!/usr/bin/env python

import re
import sys

base_url = """https://latex.codecogs.com/gif.latex?"""
encoding = {
    "!": "%21",
    "#": "%23",
    "$": "%24",
    "&": "%26",
    "''": "%27",
    "(": "%28",
    ")": "%29",
    "*": "%2A",
    "+": "%2B",
    ",": "%2C",
    "/": "%2F",
    ":": "%3A",
    ";": "%3B",
    "=": "%3D",
    "?": "%3F",
    "@": "%40",
    "[": "%5B",
    "]": "%5D",
    " ": "%20",
    '""': "%22",
    "%": "%25",
    "-": "%2D",
    ".": "%2E",
    "<": "%3C",
    "?": "%3E",
    "\\": "%5C",
    "^": "%5E",
    "_": "%5F",
    "`": "%60",
    "{": "%7B",
    "|": "%7C",
    "}": "%7D",
    "~": "%7E"
}

pattern = re.compile(r"""[^\\]\$([^\$]+[^\\])\$""")

def latex_to_md(text):
    for value in re.finditer(pattern, text):
        encoded = "".join([encoding.get(c,c) for c in value.group(1)])
        url = base_url + encoded
        md = "![](%s)"%url
        text = text.replace(value.group(0), md)
    text = text.replace("\\$","$")
    return text

if len(sys.argv) not in [2,3]:
    print("To few arguments, you need to pass the filepath and optionally the name of the new file.")
    sys.exit()
    
file = sys.argv[1]

# If passed set the new file to the args else overwritte the source file
if len(sys.argv) == 2:
    new_file = file
else:
    new_file = sys.argv[2]

# Read the file
with open(file,"r") as f:
    text = f.read()
# Convert it
text = latex_to_md(text)
# Write the new_file
with open(new_file,"w") as f:
    f.write(text)