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MapIndexed

MapIndexed[f, expr]
applies f to the elements of expr, giving the part specification of each element as a second argument to f.
MapIndexed[f, expr, levelspec]
applies f to all parts of expr on levels specified by levelspec.
nlevels 1 through n
Infinitylevels 1 through Infinity
{n}level n only
{n1,n2}levels n1 through n2
  • The default value for levelspec in MapIndexed is {1}.
  • 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 -1 consists of numbers, symbols and other objects that do not have subparts.
  • Level 0 corresponds to the whole expression.
  • With the option setting Heads->True, MapIndexed also applies to heads of expressions, and their parts.
  • MapIndexed traverses the parts of expr in a depth-first order, with leaves visited before roots. »
  • MapIndexed always effectively constructs a complete new expression, and then evaluates it.
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