Regex to extract ONLY alphanumeric words

python regex alphanumeric

GRoutar · Jan 5, 2019 · Viewed 7.2k times · Source

I am looking for a regex to extract the word that ONLY contain alphanumeic characters:

string = 'This is a $dollar sign !!'
matches = re.findall(regex, string)
matches = ['This', 'is', 'sign']

This can be done by tokenizing the string and evaluate each token individually using the following regex:

^[a-zA-Z0-9]+$

Due to performance issues, I want to able to extract the alphanumeric tokens without tokenizing the whole string. The closest I got to was

regex = \b[a-zA-Z0-9]+\b

, but it still extracts substrings containing alphanumeric characters:

string = 'This is a $dollar sign !!'
matches = re.findall(regex, string)
matches = ['This', 'is', 'dollar', 'sign']

Is there a regex able to pull this off? I've tried different things but can't come up with a solution.

Answer

There is no need to use regexs for this, python has a built in isalnum string method. See below:

string = 'This is a $dollar sign !!'

matches = [word for word in string.split(' ') if word.isalnum()]