Python简单过滤字母和数字的方法小结

crazystring = 'dade142.!0142f[., ]ad'
# 只保留数字
new_crazy = filter(str.isdigit, crazystring)
print(''.join(list(new_crazy))) #输出：1420142
# 只保留字母
new_crazy = filter(str.isalpha, crazystring)
print(''.join(list(new_crazy))) #睡出：dadefad
# 只保留字母和数字
new_crazy = filter(str.isalnum, crazystring)
print(''.join(list(new_crazy))) #输出：dade1420142fad
# 如果想保留数字0-9和小数点'.' 则需要自定义函数
new_crazy = filter(lambda ch: ch in '0123456789.', crazystring)
print(''.join(list(new_crazy))) #输出：142.0142.

import re
L = ['小明', 'xiaohong', '12', 'adf12', '14']
for i in range(len(L)):
  if re.findall(r'^[^\d]\w+', L[i]):
    print(re.findall(r'^\w+$', L[i])[0])
避开正则表达式
L = ['xiaohong', '12', 'adf12', '14', '晓明']
for x in L:
  try:
    int(x)
  except:
    print(x)

L = ['xiaohong', '12', 'adf12', '14', '晓明']
# 对于python3来说同样还可以使用string.isnumeric()方法
for x in L:
  if not x.isdigit():
    print(x)
# for x in L:
#   if not x.isnumeric():
#     print(x)

import re
x = 'a12121assa'
x = '1脚本之家1'
r1 = '[a-zA-Z0-9'!"#$%&\'()*+,-./:;<=>?@，。?★、…【】《》？“”‘'！[\\]^_`{|}~]+'
print(re.sub(r1, '', x))