The following examples illustrate the functioning or regular expressions in Python:
a. Email Filtering
The regular expressions can be efficiently used to filter emails. The regular syntax for email filtering is - ^((a-zA-Z0-9_.)+)@((a-zA-Z0-9-)+).((a-zA-Z){2,4})$
This expression is divided into three groups and tackles many cases including - when the username is alphanumeric and when it has a dot, for eg., “first.last@”. This expression will be used for top domains that contain 2-4 characters.
b. Dates Filtering
Dates can be a crucial factor while handling data filtering. The textual data that you are dealing with often contains dates. The regular expression or RegEx that extracts the data from a normal text is - ^(d{1,2})(/-)(d{1,2})(/-)(d{2,4})$
The date and the month can be up to 2 digits while the month can be up to 4 digits.