Python string substitution re.sub ()

re.sub(pattern, repl, string, count=0, flags=0)

Pattern can be a string or a regular that matches the character to be replaced, and if not, the string is not modified. \1 represents the first group

REPL is the value that will be replaced, REPL can be a string, or it can be a method. If it is a string, the backslash is processed as an escape character, such as \ n is replaced with a newline, and so on. Repl if it is a function, each matching field string executes the replacement function.

\g<1> represents the first grouping in the preceding pattern, which can be abbreviated to \1,\g<0> representing all strings that match the preceding pattern.

count is the maximum number of times that pattern is replaced, and by default 0 replaces all. Sometimes you may want to replace only one part, you can use the Count

Example 1:

A = Re.sub (R ' Hello ', ' I love the ', ' Hello World ') print (a)
' I love the World '   #hello in world Hello is replaced by I love the

Example 2:

>>> a = Re.sub (R ' (\d+) ', ' hello ', ' My Numer is "and door num is") >>> a ' My numer is Hello and door Num is hello ' #数字400 and 200 are replaced by Hello

Example 3:

A = Re.sub (R ' Hello (\w+), Nihao \1 ', R ' Emma ', ' Hello Sherry, Nihao Sherry ') >>> a ' Emma '  #\1 represents the first grouped value as sherry, Because there are two sherry, so using \1 can refer to the second one, so that the entire string is replaced by Emma

Example 4:

>>> a = Re.sub (' (\d{4})-(\d{2})-(\d{2}) ', R ' \2-\3-\1 ', ' 2018-06-07 ') >>> a ' 06-07-2018 ' >>> a = Re.sub (' (\d{4})-(\d{2})-(\d{2}) ', R ' \g<2>-\g<3>-\g<1> ', ' 2018-06-07 ') >>> a ' 06-07-2018 '  #\2 and \g<2> refer to the second group in front

Example 5:

Import redef replace_num (str): numdict = {' 0 ': ' 0 ', ' 1 ': ' One ', ' 2 ': ' Two ', ' 3 ': ' Three ', ' 4 ': ' Four ', ' 5 ': ' Five ', ' 6 ': ' Six ', ' 7 ': ' Seven ', ' 8 ': ' Eight ', ' 9 ': ' Nine '}print (Str.group ()) return Numdict[str.group ()]my_str = ' June 7, 2018 ' A = Re.sub (R ' (\d) ', Replace_num, my_str) print (a)  #每次匹配一个数字, execute the function to get the replaced value

re.subn(pattern, repl, string, count=0, flags=0)

As with the sub () function, only a tuple is returned, the number of substituted strings and replacements

　

　

Python string substitution re.sub ()