count

count(X)

X is a scalar/vector/matrix/table.

size returns the number of elements in a vector or matrix, while count returns the number of non-null elements in a vector/matrix. count can be used in a SQL query, but size cannot. For tables, size and count both return the number of rows.

count(3 NULL 5 6);
// output: 3
size(3 NULL 5 6);
// output: 4

m=1 2 3 NULL 4 5$2:3;
m;

count(m);
// output: 5
size(m);
// output: 6

t = table(1 NULL 3 as id, 3 NULL 9 as qty);
t;

count(t);
// output: 3
size(t);
// output: 3