Pattern-matching functions

Pattern-matching functions are used to match strings against regular expressions.

Pattern matching operator

Cypher supports regular expression with =~ operator. The =~ operator succeeds only if its pattern matches the entire string.

Example:

RETURN 'abc' =~ 'abc';
True

RETURN 'abc' =~ 'a';
False

RETURN 'abc' =~ '.*(b|d).*';
True

RETURN 'abc' =~ '(b|c).*';
False

Escaping in regular expressions

To use special characters (e.g. ., *) without special meaning, escape them with backslash (\).

Example:

RETURN '[email protected]' =~ '.*\\.com';
True

Case-insensitive regular expressions

To use case-insensitive regular expressions, preappend a regular expression with ?i

Example:

RETURN 'abc' =~ '(?i)A.*';
True

Regex functions

You can also use regex functions within Cypher to match, extract or replace substrings.

regexp_matches(string, pattern)

• Description: Returns true if a part of string matches the regex.
• Example: regexp_matches('aba', '^ab')
• Result: true

regexp_replace(string, pattern, replacement[, options])

• Description: Replaces the matching part of string with replacement.
• Example: regexp_replace('ababbb', 'b.b', 'a')
• Result: 'aabb'

See the options section for global replacement options.

regexp_extract(string, pattern[, group = 0])

• Description: Splits the string along the regex and extracts the first occurrence of the group.
• Example: regexp_extract('abababab', 'b.b', 0)
• Result: 'bab'

regexp_extract_all(string, pattern[, group = 0])

• Description: Splits the string along the regex and extracts all occurrences of the group.
• Example: regexp_extract_all('abababab', 'b.b', 0)
• Result: ['bab','bab']

regexp_split_to_array(string, pattern[, options])

• Description: Splits the string along the regex and extract all occurences between regex.
• Example: regexp_split_to_array('hello world 42', ' ')
• Result: ['hello','world', '42']

See the options section for global replacement options.

Options for regex functions

Global replacement options

By default, the regexp_replace function replaces only the first occurrence of the pattern in the string.

To replace all occurrences of the pattern, use the g option.

The following example replaces multiple spaces with an empty string globally across the input string:

RETURN regexp_replace('20 main   street', '\\s+', '', 'g') AS global_replace;

┌────────────────┐
│ global_replace │
│ STRING         │
├────────────────┤
│ 20mainstreet   │
└────────────────┘