rearrange: Reader-friendly smart element reordering for multidimensional...

In einops: Flexible, Powerful, and Readable Tensor Operations

Reader-friendly smart element reordering for multidimensional tensors.

Description

This operation includes functionality of transpose (axes permutation), reshape (view), squeeze, unsqueeze, stack, concatenate and other operations.

Usage

rearrange(x, expr, ..., .row_major = getOption("einops_row_major", FALSE))

einops.rearrange(
  x,
  expr,
  ...,
  .row_major = getOption("einops_row_major", FALSE)
)

Arguments

x	tensor: array, matrix, or list of arrays of the same shape and type
expr	string: reduction pattern
...	either corresponding axes lengths or a single list of them.
.row_major	logical: whether to use row-major order for the output tensor. If TRUE, the operation is performed in row-major order, but the output will be in whatever order the parent framework uses (e.g. column-major for base::array()).

Details

When composing axes, C-order enumeration is used (consecutive elements have different last axis). Find more examples in the vignettes.

Value

tensor of the same type as input, with dimensions according to output pattern

Examples

if (requireNamespace("abind", quietly = TRUE)) {

# suppose we have a set of 32 images in "h w c" format (height-width-channel)
images <- lapply(1:32, function(i) {
    as_image_tensor(array(rnorm(30*40*3), dim = c(30, 40, 3)))
})

# stacked and reordered axes to "b c h w" format
y <- rearrange(images, 'b h w c -> b c h w')

# concatenate images along height (vertical axis), 960 = 32 * 30
y <- rearrange(images, 'b h w c -> (b h) w c')

# concatenated images along horizontal axis, 1280 = 32 * 40
y <- rearrange(images, 'b h w c -> h (b w) c')

# flattened each image into a vector, 3600 = 30 * 40 * 3
y <- rearrange(images, 'b h w c -> b (c h w)')

# split each image into 4 smaller quadrants, 128 = 32 * 2 * 2
y <- rearrange(
    images, 'b (h1 h) (w1 w) c -> (b h1 w1) h w c', h1 = 2, w1 = 2
)

# space-to-depth operation
y <- rearrange(
    images, 'b (h h1) (w w1) c -> b h w (c h1 w1)', h1 = 2, w1 = 2
)

}

einops documentation built on Sept. 9, 2025, 5:29 p.m.