Match characters: match_characters

Syntax

match_characters ( op , pattern )

Input parameters

op	the dataset to be checked
pattern	the regular expression to check the Data Set or the Component against

Examples of valid syntaxes

match_characters(ds1, "[abc]+\d\d")
ds1 [ calc m1 := match_characters(ds1, "[abc]+\d\d") ]

Semantics for scalar operations

match_characters returns true if op matches the regular expression regexp, false otherwise.

The string regexp is an Extended Regular Expression as described in the POSIX standard[^1]. Different implementations of VTL may implement different versions of the POSIX standard therefore it is possible that match_characters may behave in slightly different ways.

Input parameters type

op

dataset {measure<string> _}
| component<string>
| string

pattern

component<string>
| string

Result type

result

dataset { measure<boolean> bool_var }
| component<boolean>
| boolean

Additional Constraints

If op is a Data Set then it has exactly one measure.

pattern is a POSIX regular expression.

Behaviour

The operator has the typical behaviour of the “Operators changing the data type” (see the section “Typical behaviours of the ML Operators”).

[^1]: Please note that only POSIX Extended Regular Expressions (not ERE classes) are currently supported by VTL

Examples

Given the operand dataset DS_1:

Input DS_1 (see structure)

Id_1	Id_2	Id_3	Id_4	Me_1
G	Total	Percentage	Total	AX123
R	Total	Percentage	Total	AX2J5

Example 1

DS_r:=match_characters(DS_1, "[A-Za-z]{2}[0-9]{3}");

results in (see structure):

DS_r
Id_1	Id_2	Id_3	Id_4	bool_var
G	Total	Percentage	Total	true
R	Total	Percentage	Total	false