Function _Stack

express/NeuralNetWorkOp.cpp:810–817

Stacks a list of rank-R variables into one rank-(R+1) variable. Packs the list of variables in `values` into a ariable with rank one higher than each variable in values, by packing them along the axis dimension. Given a list of length N of variables of shape (A, B, C); if axis == 0 then the output variable will have the shape (N, A, B, C). if axis == 1 then the output variable will have the shape

output: A stacked variable with the same type as `values`.
*/
VARP _Stack(VARPS values, int axis) {
    std::unique_ptr<OpT> pack(new OpT);
    pack->type                         = OpType_Pack;
    pack->main.type                    = OpParameter_PackParam;
    pack->main.value                   = new PackParamT;
    pack->main.AsPackParam()->axis     = axis;
    return (Variable::create(Expr::create(std::move(pack), values)));
}
/*Extracts crops from the input image variable and resizes them using bilinear sampling or nearest neighbor sampling (possibly with aspect ratio change)
to a common output size specified by crop_size.
Returns a variable with crops from the input image at positions defined at the bounding box locations in boxes.