How to remove punctuation marks from a string in Python 3.x using .translate()?

Question

I want to remove all punctuation marks from a text file using .translate() method. It seems to work well under Python 2.x but under Python 3.4 it doesn't seem to do anything.

My code is as follows and the output is the same as input text.

import string
fhand = open("Hemingway.txt")
for fline in fhand:
    fline = fline.rstrip()
    print(fline.translate(string.punctuation))

Answer 1

You have to create a translation table using maketrans that you pass to the str.translate method.

In Python 3.1 and newer, maketrans is now a static-method on the str type, so you can use it to create a translation of each punctuation you want to None.

import string

# Thanks to Martijn Pieters for this improved version

# This uses the 3-argument version of str.maketrans
# with arguments (x, y, z) where 'x' and 'y'
# must be equal-length strings and characters in 'x'
# are replaced by characters in 'y'. 'z'
# is a string (string.punctuation here)
# where each character in the string is mapped
# to None
translator = str.maketrans('', '', string.punctuation)

# This is an alternative that creates a dictionary mapping
# of every character from string.punctuation to None (this will
# also work)
#translator = str.maketrans(dict.fromkeys(string.punctuation))

s = 'string with "punctuation" inside of it! Does this work? I hope so.'

# pass the translator to the string's translate method.
print(s.translate(translator))

This should output:

string with punctuation inside of it Does this work I hope so