# -*- conding:utf-8 -*-
import re
txt = '这个池子的体积大约是34立方米容积'
'''role为匹配规则，re_out为替换部分格式为“\1（替换部分）”'''
def Replace(role,re_out):
 out = re.compile(role)
 String_out = out.sub(re_out,txt)
 print(String_out)
Replace(r'(这个池子的体积大约是34)(.*)',r'\1平方米')
'''
role为匹配规则，num为将要删除的元素(从1开始)
'''
def Delete(role,num):
 out = re.search(role,txt).group(num)
 string = txt.split(out)
 String_out = ''.join(string)
 print(String_out)
Delete('(这个池子的体积大约是34)(.*)(容积)',2)
def Add(role,re_out):
 out = re.compile(role)
 String_out = out.sub(re_out,txt)
 print(String_out)
Add(r'(这个池子的体积大约是34)(.{0})',r'\1的')