Level[expr, levelspec]
gives a list of all subexpressions of expr on levels specified by levelspec.

Level[expr, levelspec, f]
applies f to the sequence of subexpressions.

Details and OptionsDetails and Options

  • Level uses standard level specifications:
  • nlevels 1 through
    Infinitylevels 1 through Infinity
    {n}level only
    {n1,n2}levels through
  • Level[expr, {-1}] gives a list of all "atomic" objects in expr.
  • A positive level consists of all parts of expr specified by indices.
  • A negative level consists of all parts of expr with depth .
  • Level 0 corresponds to the whole expression.
  • With the option setting Heads->True, Level includes heads of expressions and their parts.
  • Level traverses expressions in depth-first order, so that the subexpressions in the final list are ordered lexicographically by their indices.
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