MODULES PART-6

The search() Function

The search() function searches the string for a match, and returns a Match object if there is a match.

If there is more than one match, only the first occurrence of the match will be returned:

Example

Search for the first white-space character in the string:

import re

txt = "The rain in Spain"
x = re.search("\s", txt)

print("The first white-space character is located in position:", x.start())

Output:

The first white-space character is located in position: 3

 

The split() Function

The split() function returns a list where the string has been split at each match:

Example

Split at each white-space character:

import re

txt = "The rain in Spain"
x = re.split("\s", txt)
print(x)

Output:

['The', 'rain', 'in', 'Spain']

 

Match Object

A Match Object is an object containing information about the search and the result.

Note: If there is no match, the value None will be returned, instead of the Match Object.

Example

Do a search that will return a Match Object:

import re

txt = "The rain in Spain"
x = re.search("ai", txt)
print(x) #this will print an object

 

Output:

<_sre.SRE_Match object; span=(5, 7), match='ai'>

The Match object has properties and methods used to retrieve information about the search, and the result:

.span() returns a tuple containing the start-, and end positions of the match.
.string returns the string passed into the function
.group() returns the part of the string where there was a match

Example

Print the position (start- and end-position) of the first match occurrence.

The regular expression looks for any words that starts with an upper case "S":

import re

txt = "The rain in Spain"
x = re.search(r"\bS\w+", txt)
print(x.span())

Output:

(12, 17)

Example

Print the string passed into the function:

import re

txt = "The rain in Spain"
x = re.search(r"\bS\w+", txt)
print(x.string)

Output:

The rain in Spain

Example

Print the part of the string where there was a match.

The regular expression looks for any words that starts with an upper case "S":

import re

txt = "The rain in Spain"
x = re.search(r"\bS\w+", txt)
print(x.group())

 

Output:

Spain

 

You can also much detailed explanation and more examples here:

https://www.tutorialspoint.com/python3/python_reg_expressions.htm

https://docs.python.org/3/library/re.html