ValueError: unsupported format character '

Question

I got most of the following code from here: Generating pdf-latex with python script

#!/usr/bin/env python

from __future__ import division
from functions import *
import shlex

#from Utilities import *
import os
import argparse
import subprocess

equation = '\begin{equation*}1 + \gamma\lambda B/2\end{equation*}'

content=r'''\documentclass{article}
\usepackage{graphicx,amsmath}

\begin{document}
\noindent\rotatebox{180}{\vbox{%
    %(equation)s
    }%
}
\end{document}
'''

parser=argparse.ArgumentParser()
parser.add_argument('-e', '--equation', default=equation)

args=parser.parse_args()
content%args.__dict__

print content%args.__dict__

running this code gives me the following error:

Traceback (most recent call last):
  File "latex.py", line 29, in <module>
    content%args.__dict__
ValueError: unsupported format character '
' (0xa) at index 104

anybody know what's going wrong? I've got the same error from other methods of rotating the page.

*Aside*: the string literal for `equation` should probably be a raw string literal: `equation = r'\begin ...'`. — Robᵩ, Dec 09 '13 at 20:38
@AronVietti: It is telling you that `%\n` is not a valid formatting syntax. — Martijn Pieters, Dec 09 '13 at 20:38

score 25 · Accepted Answer · answered Dec 09 '13 at 20:28

25

Any % in content is seen as a formatting placeholder. Double any that are not a placeholder:

content=r'''\documentclass{article}
\usepackage{graphicx,amsmath}

\begin{document}
\noindent\rotatebox{180}{\vbox{%%
    %(equation)s
    }%%
}
\end{document}
'''

Otherwise the % at the end of the \noindent\rotatebox{180}{\vbox{% line is seen together with the \n newline as a formatting character, hence the exception with an embedded newline.

answered Dec 09 '13 at 20:28

Martijn Pieters

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Hit this error while encoding a calculation that used modulus as a string. – cs_alumnus Oct 13 '14 at 17:23

ValueError: unsupported format character '

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