Wolfram Language & System 10.4 (2016)|Legacy Documentation

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returns True if an element of list matches form, and False otherwise.

tests all parts of list specified by levelspec.

represents an operator form of MemberQ that can be applied to an expression.

Details and OptionsDetails and Options

  • form can be a pattern.
  • The first argument of MemberQ can have any head, not necessarily List.
  • MemberQ[list,form] immediately tests whether any expression in list matches form; Element[x,dom] asserts that x is an element of the symbolic domain dom.
  • MemberQ uses standard level specifications:
  • nlevels through n
    Infinitylevels through Infinity
    {n}level n only
    {n1,n2}levels through
  • The default value for levelspec in MemberQ is .
  • A positive level n consists of all parts of expr specified by n indices.
  • A negative level -n consists of all parts of expr with depth n.
  • Level consists of numbers, symbols, and other objects that do not have subparts.
  • Level corresponds to the whole expression.
  • With the option setting Heads->True, MemberQ looks at heads of expressions and their parts.
  • MemberQ works on associations, testing values but not keys.
  • MemberQ[form][expr] is equivalent to MemberQ[expr,form].
Introduced in 1988
| Updated in 2014