Regular Expressions
- Regular expression is a sequence of characters that defines a search pattern.
- It is a impressive tool for searching a pattern.
Example
string_a = re.search(r'portal', 'portal for folks')
print(string_a)
print(string_a.group())
print('Start from the Index:', string_a.start())
print('Ends at the Index:', string_a.end())
output:
<re.Match object; span=(0, 6), match='portal'>
portal
Start from the Index: 0
Ends at the Index: 6
Meta Characters
The below table shows the list of MetaCharacters are used in regex
Applications
Data Mining:
- Data mining is the process of sorting large amounts of data to identify patterns and relationships that can help solve business problems through data analysis.
Data Validation:
- Data validation is the process of checking and validating data that is collected before it is used.
Basic regular expressions.
Character Classes
- Character classes allow us to match a single character set against a possible character set. You can also place a character class inside the square brackets.
Ranges
- The range provides the versatility to match a text in the range. The hyphen character within the character class represents a range.
Shortcuts in RegEx.
- \w – matches a word character
- \d – matches digit character
- \s – matches white space character (space, tab, newline, etc.)
- \b – matches a zero-length character
Negation
- Negation inverts character classes. Finds a match excluding the reversed character or range of reversed characters specified in the character class.
Ends of String
- The caret character matches the beginning of the string and the $ character matches at the end of the string.
Any Character
- The period character represents any single character except the character classes enclosed in parentheses.
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