# Replace with a regular expression

Shape / columns

A variant of [Match with a regular expression](https://meridian.online/operations/match-with-a-regular-expression).

Replace or remove the parts of a value that match a pattern, optionally using backreferences.

Page: <https://meridian.online/operations/match-with-a-regular-expression/replace-with-a-regular-expression>

## Status

Runs as a SQL step.

arcform carries it as a `sql:` step today.

## The DuckDB step

replace the parts a pattern matches, with a backreference

It reads the `orders` table the proofs share. Create it first:

```sql
CREATE TABLE orders AS SELECT * FROM (VALUES
  (1,  'Alice Ng',      'north', DATE '2026-01-03', 120.00, 'widget', 'a|b',   '{"channel":"web","items":[1,2]}'),
  (2,  'alice ng',      'north', DATE '2026-01-05',  80.50, 'gadget', 'b',     '{"channel":"shop","items":[3]}'),
  (3,  'Bob  Okafor',   'south', DATE '2026-01-05', 300.00, 'widget', 'a|c',   '{"channel":"web","items":[4,5,6]}'),
  (4,  'Carla Díaz',    'east',  DATE '2026-01-09',  NULL,  'gizmo',  NULL,    '{"channel":"web","items":[]}'),
  (5,  'Bob Okafor',    'south', DATE '2026-01-12',  45.25, 'gadget', 'c',     '{"channel":"phone","items":[7]}'),
  (6,  'Dev Patel',     'west',  DATE '2026-01-12', 510.00, 'widget', 'a',     '{"channel":"web","items":[8,9]}'),
  (7,  'Carla Diaz',    'east',  DATE '2026-01-20',  99.99, 'gizmo',  'b|c',   '{"channel":"shop","items":[10]}'),
  (8,  'Dev Patel',     'west',  DATE '2026-02-02', 510.00, 'widget', 'a',     '{"channel":"web","items":[8,9]}'),
  (9,  'Eve Larsen',    NULL,    DATE '2026-02-03',  15.00, 'gadget', NULL,    '{"channel":"web","items":[11]}'),
  (10, 'Alice Ng',      'north', DATE '2026-02-10', 220.00, 'gizmo',  'a|b|c', '{"channel":"phone","items":[12,13]}')
) t(order_id, customer, region, order_date, amount, product, tags, meta);
```

Then run the statement:

```sql
CREATE TEMP TABLE result AS
SELECT order_id, regexp_replace(customer, '^(\S+)\s+(\S+)$', '\2, \1') AS surname_first, regexp_replace(product, '[aeiou]', '', 'g') AS consonants FROM orders;
SELECT * FROM result;
SELECT CASE WHEN ((SELECT surname_first FROM result WHERE order_id = 3) = 'Okafor, Bob' AND (SELECT surname_first FROM result WHERE order_id = 1) = 'Ng, Alice' AND (SELECT list(DISTINCT consonants ORDER BY consonants) FROM result) = ['gdgt', 'gzm', 'wdgt']) THEN 'as expected' ELSE error('names were not turned surname first, or vowels were not removed from the products') END AS verdict;
```

It needs nothing installed beyond DuckDB itself.

## What other tools call it

Meridian's classification; an independent blind rating agreed on 95.7% of 324 rows (variant, version 3).

- Duckle: [`Regex Replace`](https://github.com/slothflowlabs/duckle/blob/f85f8960edfb6efbf4cb89d58a7b32e16df0e867/website/docs/components.html) (read 2026-09-25)
- Ibis: [`RegexReplace`](https://github.com/ibis-project/ibis/blob/05d2b293344e86cb41c1a426071734f7e270335a/ibis/expr/operations/strings.py) (read 2026-09-27)
- Apache NiFi: [`ReplaceText`](https://nifi.apache.org/components/org.apache.nifi.processors.standard.ReplaceText/) (read 2026-09-27)
- OpenRefine: [`Find and replace`](https://openrefine.org/docs/manual/grelfunctions#find-and-replace) (read 2026-09-27)
- RapidMiner Studio: [`Remove Document Parts`](https://docs.rapidminer.com/latest/studio/operators/extensions/Text%20Processing/transformation/remove_document_parts.html) (read 2026-09-27)
- RapidMiner Studio: [`Replace`](https://docs.rapidminer.com/latest/studio/operators/blending/values/replace.html) (read 2026-09-27)
- RapidMiner Studio: [`Replace (In Database)`](https://docs.rapidminer.com/latest/studio/operators/extensions/In-Database%20Processing/indb_blending/indb_replace.html) (read 2026-09-27)
- RapidMiner Studio: [`Replace Tokens`](https://docs.rapidminer.com/latest/studio/operators/extensions/Text%20Processing/transformation/replace_tokens.html) (read 2026-09-27)
- VisiData: [`addcol-regex-subst`](https://github.com/saulpw/visidata/blob/7609212ec2febafa9caba7183cbebfaf49627909/visidata/features/regex.py#L141) (read 2026-09-23)
- VisiData: [`addcol-subst`](https://github.com/saulpw/visidata/blob/7609212ec2febafa9caba7183cbebfaf49627909/visidata/deprecated.py#L232) (read 2026-09-23)
- VisiData: [`setcol-regex-subst`](https://github.com/saulpw/visidata/blob/7609212ec2febafa9caba7183cbebfaf49627909/visidata/features/regex.py#L142) (read 2026-09-23)
- VisiData: [`setcol-regex-subst-all`](https://github.com/saulpw/visidata/blob/7609212ec2febafa9caba7183cbebfaf49627909/visidata/features/regex.py#L143) (read 2026-09-23)
- VisiData: [`setcol-subst`](https://github.com/saulpw/visidata/blob/7609212ec2febafa9caba7183cbebfaf49627909/visidata/deprecated.py#L233) (read 2026-09-23)
- VisiData: [`setcol-subst-all`](https://github.com/saulpw/visidata/blob/7609212ec2febafa9caba7183cbebfaf49627909/visidata/deprecated.py#L234) (read 2026-09-23)