colCollapse {DelayedMatrixStats} | R Documentation |
Extracts one cell per row (column) from a matrix. The implementation is optimized for memory and speed.
colCollapse(x, idxs, cols = NULL, dim. = dim(x), ...) rowCollapse(x, idxs, rows = NULL, dim. = dim(x), ...) ## S4 method for signature 'DelayedMatrix' colCollapse(x, idxs, cols = NULL, dim. = dim(x), force_block_processing = FALSE, ...) ## S4 method for signature 'DelayedMatrix' rowCollapse(x, idxs, rows = NULL, dim. = dim(x), force_block_processing = FALSE, ...)
x |
A NxK DelayedMatrix. |
idxs |
An index |
cols |
A |
dim. |
An |
... |
Additional arguments passed to specific methods. |
rows |
A |
force_block_processing |
|
Returns a vector
of length N (K).
Matrix indexing to index elements in matrices and arrays,
cf. [
().
# A DelayedMatrix with a 'matrix' seed dm_matrix <- DelayedArray(matrix(c(rep(1L, 5), as.integer((0:4) ^ 2), seq(-5L, -1L, 1L)), ncol = 3)) # A DelayedMatrix with a 'HDF5ArraySeed' seed # NOTE: Requires that the HDF5Array package is installed library(HDF5Array) dm_HDF5 <- writeHDF5Array(matrix(c(rep(1L, 5), as.integer((0:4) ^ 2), seq(-5L, -1L, 1L)), ncol = 3)) # Extract the 4th row as a vector # NOTE: An ordinary vector is returned regardless of the backend of # the DelayedMatrix object colCollapse(dm_matrix, 4) colCollapse(dm_HDF5, 4) # Extract the 2nd column as a vector # NOTE: An ordinary vector is returned regardless of the backend of # the DelayedMatrix object rowCollapse(dm_matrix, 2) rowCollapse(dm_HDF5, 2)