Split

is a monadic primitive function which reduces the rank of its argument by converting one of its axes to one level of nesting. The axis to move defaults to the last axis, but a different axis can be chosen using function axis. It shares its glyph  with the dyadic function Drop. Split is the inverse of Mix in the sense that the latter undoes the enclosing that Split introduced.

Examples
The result of Split on a non-scalar array is always a nested array whose elements are vectors. The rank of  is   (original rank minus 1), its shape is   (original shape with K-th axis removed), and the shape of each element is.

Split is a no-op to a scalar.

Alternatives
Most dialects do not have Split. Instead, they can use Enclose with bracket axis or the Rank operator: It is common to split a higher-rank array into its constituent major cells. The behaviour of Split on matrices might mislead to the belief that this is what the primitive does. However, it isn't so for vectors or arrays of higher rank than 2. Instead, the solution is to use or  or  :

Lessons

 * APL Cultivation

Documentation

 * Dyalog