slice method
Implementation
FVector slice(int offset, int length) {
FVector newVec = FVector.zero(length);
assert(offset + length <= nRows && offset >= 0 && length > 0);
var dest32 = newVec.columnData.buffer.asInt32List();
var source32 = columnData.buffer.asInt32List(offset * 4);
int start = 0;
if (offset % 4 == 0) {
for (int i = 0; i < length ~/ 4; ++i)
newVec.columnData[i] = columnData[i + offset ~/ 4];
start = length - (length % 4);
}
for (int i = start; i < length; ++i) {
dest32[i] = source32[i];
}
return newVec;
}