# CombineIndices: Combine weighted indices of n-dimensional arrays In ClimProjDiags: Set of Tools to Compute Various Climate Indices

 CombineIndices R Documentation

## Combine weighted indices of n-dimensional arrays

### Description

Function to combine climate indices for multiple models through addition, subtraction, division or averaging, optionally applying weights to each index.

### Usage

``````CombineIndices(indices, weights = NULL, operation = "mean")
``````

### Arguments

 `indices` List of n-dimensional arrays with equal dimensions to be combined. `weights` Vector of weights for the indices, whose length is the same as the list of parameter `indices`. If not provided, a weight of 1 is assigned to each index. If `operation = 'mean'` the weights are normalized to sum 1 all together. `operation` The operation for combining the indices, either `"mean"` (default), `"add"`, `"subtract"` or `"divide"`.

### Value

An array of the same dimensions as one of the elements in the parameter `indices`.

### Examples

``````a <- matrix(rnorm(6), 2, 3)
b <- matrix(rnorm(6), 2, 3)

comb_ind <- CombineIndices(indices = list(a, b), weights = c(2, 1),
print(comb_ind)

a <- rnorm(24)
dim(a) <- c(lon = 2, lat = 3, mod = 4)
b <- rnorm(24)
dim(b) <- c(lon = 2, lat = 3, mod = 4)
comb_ind <- CombineIndices(indices = list(a, b), weights = c(2, 1),