TransposeColumn
The TransposeColumn is an executable Link that will create the matrix transpose of nested Links or collections of vector values.
The anticipated use is to take search results, typically from QueryLink, which are returned as rows, and to repackage them as vector-columns. This works effectively the same way as FloatColumn or LinkColumn, except that it will generate multiple columns in one go. Recall that Values correspond to C++ vectors, and are directly accessible as C++ 'std::vector<T>' types.
For example,
TransposeColumn
Number 1 2 3
Number 4 5 6
when executed will return
LinkValue FloatValue 1 4 FloatValue 2 5 FloatValue 3 6
NumberNode vectors are automatically converted to FloatValue; this is to avoid the RAM overhead of storing them into the AtomSpace. Use [[LinkSignature(cog-execute!
(LinkSignature
(Type 'Float32Value)
(Minus (Time) (Number 2))
(Time)
(Plus (Time) (Number 2))))
Link]] if you wish to convert back to NumberNodes.
Similarly,
TransposeColumn
List
List
Item "a"
Item "b"
Item "c"
List
Item "d"
Item "e"
Item "f"
when executed, will return
LinkValue
LinkValue
Item "a"
Item "d"
LinkValue
Item "b"
Item "e"
LinkValue
Item "c"
Item "f"
The ListLink's are converted to LinkValue to avoid the overhead of storing the result in the AtomSpace. Use CollectionOfLink to convert the LinkValues to explicit Links.
A large, complicated example can be found in the examples/pattern-matcher/vector-column.scm example.
