This is documentation for Mathematica 7, which was
based on an earlier version of the Wolfram Language.
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Count[list, pattern]
gives the number of elements in list that match pattern.
Count[expr, pattern, levelspec]
gives the total number of subexpressions matching pattern that appear at the levels in expr specified by levelspec.
  • Count uses standard level specifications:
nlevels 1 through n
Infinitylevels 1 through Infinity
{n}level n only
{n1,n2}levels n1 through n2
  • The default value for levelspec in Count 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, Count looks at heads of expressions and their parts.
Count how many times b occurs:
Count how many times b occurs:
Click for copyable input
Count works with patterns:
Count the number of elements not matching b:
Count occurrences of b down to level 2:
Count works with any head, not just List:
Count the total number of symbols in an expression:
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