ClimProjDiags (version 0.3.4)

Subset: Subset a Data Array

Description

This function allows to subset (i.e. slice, take a chunk of) an array, in a similar way as done in the function take() in the package plyr. There are two main snprovements:

First, the input array can have dimension names, either in names(dim(x)) or in the attribute 'dimensions'. If both exist, names(dim(x)) is prioritized. The dimensions to subset along can be specified via the parameter along either with integer indices or either by their name.

Second, there are additional ways to adjust which dimensions are dropped in the resulting array: either to drop all, to drop none, to drop only the ones that have been sliced or to drop only the ones that have not been sliced.

Usage

Subset(x, along, indices, drop = FALSE)

Value

An array with similar dimensions as the x input, but with trimmed or dropped dimensions.

Arguments

x

A named multidimensional array to be sliced. It can have dimension names either in names(dim(x)) or in the attribute 'dimensions'.

along

A vector with references to the dimensions to take the subset from: either integers or dimension names.

indices

A list of indices to take from each dimension specified in 'along'. If a single dimension is specified in 'along', it can be directly provided as an integer or a vector.

drop

Whether to drop all the dimensions of length 1 in the resulting array, none, only those that are specified in 'along', or only those that are not specified in 'along'. The possible values are: 'all' or TRUE, 'none' or FALSE, 'selected', and 'non-selected'. The default value is FALSE.

Examples

#Example synthetic data:
# Dimension has name already
data <- 1:(2 * 3 * 372 * 1)
dim(data) <- c(time = 372, lon = 2, lat = 3, model = 1)
data_subset <- Subset(data, c('time', 'model'), 
                     list(1:10, TRUE), drop = 'selected')
dim(data_subset)
# Use attributes 'dimensions'
data <- array(1:(2 * 3 * 372 * 1), dim = c(2, 3, 372, 1))
attributes(data)[['dimensions']] <- c('lat', 'lon', 'time', 'model')
data_subset <- Subset(data, c('lon', 'lat'), list(1, 1), drop = TRUE)
dim(data_subset)