WOLFRAM

Wolfram Language & System Documentation Center
General::level

General::level

Details

  • This message is generated when a level specification does not have the expected form.
  • A level specification is normally expected to be either an integer or a list of one or two integers.
  • Level specifications are used by Apply, Cases, Count, DeleteCases, FreeQ, Level, Map, MapIndexed, MemberQ, Position, Scan, Select, and other functions.
  • Level specifications indicate the depth within an expression that should be inspected or modified.
  • Off[message] switches off the message; On[message] switches it on. For example: Off[General::level].

Examples

Basic Examples  (1)

The form of the level specification in MemberQ is incorrect:

This shows a correct way to specify levels 0, 1, and 2 in an expression: