Question

i have a noob question.

I have a record in a table that looks like ‘\1abc’

I then use this string as a regex replacement in re.sub("([0-9])",thereplacement,"2")

I’m a little confused with the backslashes. The string i got back was "\\1abc"

Answer 1

Are you using python interactivly?

In regular string you need to escape backslashes in your code, or use r”…” (Link to docs). If you are running python interactivly and don’t assign the results from your database to a variable, it’ll be printed out using it’s __repr__() method.

>>> s = "\\1abc"
>>> s
'\\1abc' # <-- How it's represented in Python code
>>> print s
\1abc # <-- The actual string

Also, your re.sub is a bit weird. 1) Maybe you meant [0-9] as the pattern? (Matching a single digit). The arguments are probably switche too, if thereplacement is your input. This is the syntax:

re.sub(pattern, repl, string, count=0)

So my guess is you expect something like this:

>>> s_in  = yourDbMagic() # Which returns \1abc
>>> s_out = re.sub("[0-9]", "2", s_in)
>>> print s_in, s_out
\1abc \2abc

Edit: Tried to better explain escaping/representation.