Leave only letters and numbers in the string using a regex, in pyton

Question

我有字符串，例如： '1212kk , l ' 使用正则表达式，我必须去掉除数字和字母以外的所有内容，然后得到： '1212kkl'

Answer 1

Use the str.isalnum() which chekcs if its either letter or digit:

text = "1212kk , l"

# Option 1:
# The `x for x in text` goes on string characters
# The `if x.isalnum()` filters in only letters and digits
# The `''.join()` takes the filtered list and joins it to a string
filtered = ''.join([x for x in text if x.isalnum()])

# Option 2:
# Applay `filter` of `text` characters that `str.isalnum` returns `True` for them
# The `''.join()` takes the filtered list and joins it to a string
filtered = ''.join(filter(str.isalnum, text))

# 1212kkl
print(filtered )