Python Punctuation and Whitespace (string.punctuation)Use the string.punctuation property and print all punctuation. Test for punctuation chars like periods and commas.
Punctuation. A string contains letters, whitespace, numbers. And it has punctuation: these characters include commas and periods and semicolons.
With Python, we can access the string.punctuation constant. This contains all the common punctuation characters. It can be tested and used in programs.
In this first example we use a for-in loop over the string.punctuation characters. We print each character with surrounding brackets.for
Note: The string.punctuation values do not include Unicode symbols or whitespace characters.
Python program that uses string.punctuation
# Display punctuation.
for c in string.punctuation:
print("[" + c + "]")
In operator use.
Here we use the in-operator on the string.punctuation constant. This allows us to test whether a char in a string is a punctuation character.In
Python program that tests for punctuation
# An input string.
name = "hey, my friend!"
for c in name:
# See if the char is punctuation.
if c in string.punctuation:
print("Punctuation: " + c)
With the "in" operator and the string.punctuation constant, we can remove all punctuation chars from a string.
Note: We add each character to our result that is not punctuation. Spaces (which are not punctuation) are kept.
Python program that removes punctuation from string
result = ""
for c in value:
# If char is not punctuation, add it to the result.
if c not in string.punctuation:
result += c
# Test our method.
temp = "hello, friend!... welcome."
hello, friend!... welcome.
hello friend welcome
Let us look at another occasionally-helpful constant in the string module: string.whitespace. This too can be looped over or tested.
Tip: Instead of testing constant strings with "in," consider using methods like isspace().
Python program that uses string.whitespace
print(" " in string.whitespace)
print("\n" in string.whitespace)
print("X" in string.whitespace)
the in-operator is fast. But it will not outperform a specialized lookup table. We could use a dictionary to store a value indicating whether a char is punctuation or not.Dictionary
A review. Python contains many helpful constants in its string module. For example, we can test whitespace, digits, punctuation. We avoid writing these characters out in special code.
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