A raw string literal tells Python not to process escape sequences when it creates a string. Put `r` immediately before the opening quote: `r"\t"` contains a backslash and `t`, rather than a tab. A raw string is still an ordinary string; only the way it is written changes. section 16.3.1
Two practical rules:
- Use `r` or `R` with single, double, or triple quotes. A prefix makes no visible difference when the string contains no escape sequences. section 16.3.1
- For a regular expression, raw notation leaves backslashes for the regex engine to interpret. It prevents Python’s string processing from interpreting them first; it does not disable regex special sequences. section 16.3 section 16.3.1
r"Hello" == "Hello"
True
r"\the" == "\\the"
True
r"\the" == "\the"
False
print(r"\the")
\the
print("\the")
he
Compare the equality checks and printed output: raw `\t` stays as two characters, while the ordinary string begins with a tab. section 16.3.1
Writing Python code into a module file
If a triple-quoted string contains module code with `"\n"`, an ordinary outer string turns that sequence into a newline before the code is written. Prefix the outer triple quotes with `r`, as in `f.write(r"""...""")`, to preserve the code’s backslash and `n`. This fixes the premature substitution, not unrelated errors in the generated module. section 10.8.2
