Sub-string extraction: substr

Syntax

substr ( op, start, length )

Input parameters

op	the operand
start	the starting digit (first character) of the string to be extracted
length	the length (number of characters) of the string to be extracted

Examples of valid syntaxes

substr  ( DS_1,  2 ,  3 )
substr  ( DS_1, 2 )
substr  ( DS_1, _ , 3 )
substr  ( DS_1 )

Semantics for scalar operations

The operator extracts a substring from op, which must be string type. The substring starts from the startth character of the input string and has a number of characters equal to the length parameter.

• If start is omitted, the substring starts from the 1st position.

• If length is omitted or overcomes the length of the input string, the substring ends at the end of the input string.

• If start is greater than the length of the input string, an empty string is extracted.

For example:

substr (“abcdefghijklmnopqrstuvwxyz”, 5 , 10 ) gives: “efghijklmn”

substr (“abcdefghijklmnopqrstuvwxyz”, 25 , 10 ) gives: “yz”

substr (“abcdefghijklmnopqrstuvwxyz”, 30 , 10 ) gives: “”

Input parameters type

op

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

start

component < integer [ value >= 1 ] >
| integer [ value >= 1 ]

length

component < integer [ value >= 0 ] >
| integer [ value >= 0 ]

Result type

result

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

Additional Constraints

None.

Behavior

As for the invocations at Data Set level, the operator has the behaviour of the “Operators applicable on one Scalar Value or Data Set or Data Set Component”. As for the invocations at Component or Scalar level, the operator has the behaviour of the “Operators applicable on more than two Scalar Values or Data Set Components” (see the section “Typical behaviours of the ML Operators”).