Subset and replace tensor values — cudatensor-subset • cudaverse

Tensor indices follow ordinary one-based R array semantics. Subsetting returns a cudatensor, including when a single value is selected. Replacement preserves the tensor dtype; fractional values therefore cannot be assigned to an integer tensor.

Usage

# S3 method for class 'cudatensor'
x[..., drop = TRUE]

# S3 method for class 'cudatensor'
x[...] <- value

Arguments

x: A cudatensor.
...: One-based R array indices.
drop: Whether dimensions of length one are dropped.
value: Numeric replacement values or another cudatensor.

Value

A cudatensor on the same device as x.

Details

Backends may implement value gathering and replacement directly. The native CUDA backend evaluates only R index metadata on the host and keeps tensor values on the device. A selection whose linear indices form one increasing contiguous range becomes an allocation-free view that shares the source device allocation; other supported selections use a device gather. Compatibility backends without indexing operations use a recorded CPU round trip. Subscripts containing NA currently use the compatibility path. A replacement tensor on the same device and backend is cast to the target floating dtype on that device before replacement. Integer targets retain exact host validation for non-integer replacement values.