Apply.Rd

% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/Apply.R
\name{Apply}
\alias{Apply}
\title{Wrapper for Applying Atomic Functions to Arrays.}
\usage{
Apply(data, target_dims = NULL, AtomicFun, ..., output_dims = NULL,
  margins = NULL, ncores = NULL)
}
\arguments{
\item{data}{A single object (vector, matrix or array) or a list of objects. They must be in the same order as expected by AtomicFun.}

\item{target_dims}{List of vectors containing the dimensions to be input into AtomicFun for each of the objects in the data. These vectors can contain either integers specifying the dimension position, or characters corresponding to the dimension names. This parameter is mandatory if margins is not specified. If both margins and target_dims are specified, margins takes priority over target_dims.}

\item{AtomicFun}{Function to be applied to the arrays.}

\item{...}{Additional arguments to be used in the AtomicFun.}

\item{output_dims}{Optional list of vectors containing the names of the dimensions to be output from the AtomicFun for each of the objects it returns (or a single vector if the function has only one output).}

\item{margins}{List of vectors containing the margins for the input objects to be split by. Or, if there is a single vector of margins specified and a list of objects in data, then the single set of margins is applied over all objects. These vectors can contain either integers specifying the dimension position, or characters corresponding to the dimension names. If both margins and target_dims are specified, margins takes priority over target_dims.}

\item{ncores}{The number of multicore threads to use for parallel computation.}
}
\value{
List of arrays or matrices or vectors resulting from applying AtomicFun to data.
}
\description{
This wrapper applies a given function, which takes N [multi-dimensional] arrays as inputs (which may have different numbers of dimensions and dimension lengths), and applies it to a list of N [multi-dimensional] arrays with at least as many dimensions as expected by the given function. The user can specify which dimensions of each array (or matrix) the function is to be applied over with the \code{margins} or \code{target_dims} option. A user can apply a function that receives (in addition to other helper parameters) 1 or more arrays as input, each with a different number of dimensions, and returns any number of multidimensional arrays. The target dimensions can be specified by their names. It is recommended to use this wrapper with multidimensional arrays with named dimensions.
}
\details{
When using a single object as input, Apply is almost identical to the apply function. For multiple input objects, the output array will have dimensions equal to the dimensions specified in 'margins'.
}
\examples{
#Change in the rate of exceedance for two arrays, with different 
#dimensions, for some matrix of exceedances.
data = list(array(rnorm(2000), c(10,10,20)), array(rnorm(1000), c(10,10,10)), 
            array(rnorm(100), c(10, 10)))
test_fun <- function(x, y, z) {((sum(x > z) / (length(x))) / 
                               (sum(y > z) / (length(y)))) * 100}
margins = list(c(1, 2), c(1, 2), c(1,2))
test <- Apply(data, margins = margins, AtomicFun = "test_fun")
}
\references{
Wickham, H (2011), The Split-Apply-Combine Strategy for Data Analysis, Journal of Statistical Software.
}