# Formatting numbers for LaTeX

Filed under latex.

The following Python function converts a float to a LaTeX-friendly string formatted to three significant digits and with very large or small values in presented in standard notation.

"""Format a number for inclusion in LaTeX.

"""
from scipy.stats import cauchy

def format_for_latex(x, p=3):
"""Convert a float to a LaTeX-formatted string displaying the value to p significant
digits and in standard form.

Args:
x (float): Value.
p (:obj:int, optional): Number of significant digits. Default is 3.

Return:
s (str): Formatted value.
"""

def _f(x, p):
s = "{:g}".format(float("{:.{p}g}".format(x, p=3)))
n = p - len(s.replace(".", "").replace("-", "").lstrip("0"))
s += "0" * n
return s

if abs(x) < 10 ** -p or abs(x) > 10 ** (p + 1):
a, b = str("%e" % x).split("e")
return "$%s$" % r"%s \times 10^{%i}" % (_f(float(a), p), int(b))

return "$%s$" % _f(x, p)

def test():
X = cauchy.rvs(size=100000)
for x in X:
print(x, format_for_latex(x))

if __name__ == "__main__":
test()



This is probably not the best way to do it. I’m sure there is a much more elegant regex-only solution. I haven’t tested it exhaustively with different values of p. But it seems to do the job.

## Version history

• Originally posted October 04, 2019.

## Related posts

• All posts filed under latex.