> perl -ple "s/([^\w\s])/sprintf(q#%%%2X#, ord $1)/ge" somefile.txt
Hi Andrew,
Give me a second. I'm trying to understand the command line switches:
(Looking in 'perl --help'...)
-p assume loop like -n but print line also, like sed
-l[octal] enable line ending processing, specifies line terminator
-e program one line of program (several -e's allowed, omit programfile)
and the regular expression modifiers there --- 'g' and 'e' --- mean ...
(reading 'perldoc perlop'...)
g Match globally, i.e., find all occurrences.
e Evaluate the right side as an expression.
Ok, I have a better idea of what's going on here now. This takes a file,
and translates every non-whitespace character into a hex string. That's a
dense one-liner.
> How would you convert this to a python equivalent using the re or
> similar module?
The substitution on the right hand side in the Perl code actually
is evaluated rather than literally substituted. To get the same effect
from Python, we pass a function off as the substituting value to re.sub().
For example, we can translate every word-like character by shifting it
one place ('a' -> 'b', 'b' -> 'c', etc...)
###############################################
>>> import re
>>> def rot1(ch):
... return chr((ord(ch) + 1) % 256)
...
>>> def rot1_on_match(match):
... return rot1(match.group(0))
...
>>> re.sub(r'\w', rot1_on_match, "hello world")
'ifmmp xpsme'
###############################################
> I've begun reading about using re expressions at
> http://www.amk.ca/python/howto/regex/ but I am still hazy on implementation.
The part in:
http://www.amk.ca/python/howto/regex/regex.html#SECTION000620000000000000000
that talks about a "replacement function" is relevant to what you're
asking. We need to provide a replacement function to simulate the
right-hand-side "evaluation" that's happening in the Perl code.
Good luck!
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