Regular Expression

Character types

• \w matches with any alphanumeric character

• . matches to all characters, including symbols

• \d matches to all single digits [0-9]

• \s matches to all single spaces 

• \. matches to the period character

import re
re.findall("\w", "h32rb17")

import re
re.findall("\d", "h32rb17")

Quantify occurrences

• + symbol represents one or more occurrences of a specific character.
• * symbol represents zero, one, or more occurrences of a specific character.
• \d{2} instructs Python to return all matches of exactly two single digits
• \d{1,3} 數字 1 - 3 位數

import re
re.findall("\d+", "h32rb17")

import re
re.findall("\d*", "h32rb17")

import re
re.findall("\d{2}", "h32rb17 k825t0m c2994eh")

import re
re.findall("\d{1,3}", "h32rb17 k825t0m c2994eh")