number -- count how many elements of a list satisfy a condition

number -- count how many elements of a list satisfy a condition

number(x,f) -- the number of elements e of the list x for which f(e) is true.

See also:

positions -- which elements of a list satisfy a condition

select -- select elements from a list or hash table

Code:

     -- ../../../Macaulay2/m2/lists.m2:38
     number = x -> # select x