python写的掉空格数字字母的方法

def tripNumsAlpha():
'''patt=re.compile(r"[^0-9]") then we would get like str1=''.join(re.findall(patt,"1215北京"))
str1=>'北京'.Now you see what you want to .
'''
import re

patt=re.compile(r"[^0-9a-zA-Z]")
lis1=[]

with open('D:\\clrename\\clearspace.txt', 'r') as f:
for it in f.readlines():
str1=''.join(re.findall(patt,it))
lis1.append(str.lstrip(str1))

f.close()

with open('D:\\clrename\\clearspace-out.txt', 'w+') as f1:
for it in lis1:
print(it)
f1.writelines(it)
f1.close()
print("-"*4+"Finished"+"-"*4)