Question

Suppose I have the following string in Python:

>>> example="""
... \nthird line
... [\t] <-tab in there
... [\n] <-\\n in there
... \v vtab
... 1\b2 should be only '2'
... this\rthat <- should be only 'that'
... """

If I print that, the various escaped characters (like \t for a tab) are interpolated into a human readable form:

>>> print example


third line
[   ] <-tab in there
[
] <-\n in there

 vtab
2 should be only '2'
that <- should be only 'that'

What if I want to only produce a string with the various escape codes expanded or interpreted without printing it? Somthing like:

>>> exp_example = example.expandomethod()

(I have looked at the various string methods, decode, and format but none are working as in this example.)

---

Edit

OK — Thanks for the help for the thick scull on my part. I was convinced that these strings were being parsed, which they are, but it the display of them that was fooling me.

I worked this out in my own mind:

>>> cr='\012'   # CR or \n in octal
>>> len(cr)
1
>>> '123'+cr
'123\n'
>>> '123\012' == '123\n'
True

Answer 1

As others have stated, when you type in your escaped string, or Python first interprets the string, the escape character \ and the character following are reduced to the single targeted character.

However — if you are constructing a string that with to goal of producing unprintable characters from their escape sequence, str.decode([encoding[, errors]]) does what you want:

>>> s='string'
>>> esc='\\'
>>> n='n'
>>> st=s+esc+n+'next line'
>>> print st
string\nnextline
>>> print st.decode('string_escape')
string
next line

And this:

>>> ''.join(['\\','n','\\','t'])=='\n\t'
False

is a different result than this:

>>> ''.join(['\\','n','\\','t']).decode('string_escape')=='\n\t'
True