subtuple

subtuple(X, range)

X is a tuple of vectors with the same length.

range is a pair of integers indicating a range. The lower bound is inclusive and the upper bound is exclusive.

Create a read-only view of a subarray of each vector in X almost instantly. In contrast, it takes time to create a new tuple of vectors.

Example 1:

x=(1..10, 11..20, 21..30, 31..40)
subtuple(x, 2:4);
// output
([3,4],[13,14],[23,24],[33,34])

Example 2

m=1000.0
n=20000000
a=(rand(m,n), rand(m,n))
k=10000000;
timer each(avg, a.subtuple(0:k));
// output
Time elapsed: 30.87 ms

timer each(avg, (a[0][0:k], a[1][0:k]));
// output
Time elapsed: 46.508 ms

Example 3. Subtuples are read-only.

x=(1..10, 11..20)
subtuple(x, 2:4)=([4, 5], [14, 15]);
// output
Syntax Error: [line #2] Please use '==' rather than '=' as equal operator in non-sql expression.