MATLAB Language Usage of `accumarray()` Function
Introduction
accumarray allows to aggregate items of an array in various ways, potentially applying some function to the items in the process. accumarray can be thought of as a lightweight reducer (see also: Introduction to MapReduce ).
This topic will contain common scenarios where accumarray is especially useful.
Syntax
- accumarray(subscriptArray, valuesArray)
- accumarray(subscriptArray, valuesArray, sizeOfOutput)
- accumarray(subscriptArray, valuesArray, sizeOfOutput, funcHandle)
- accumarray(subscriptArray, valuesArray, sizeOfOutput, funcHandle, fillVal)
- accumarray(subscriptArray, valuesArray, sizeOfOutput, funcHandle, fillVal, isSparse)
Parameters
| Parameter | Details |
|---|---|
subscriptArray | Subscript matrix, specified as a vector of indices, matrix of indices, or cell array of index vectors. |
valuesArray | Data, specified as a vector or a scalar. |
sizeOfOutput | Size of output array, specified as a vector of positive integers. |
funcHandle | Function to be applied to each set of items during aggregation, specified as a function handle or []. |
fillVal | Fill value, for when subs does not reference each element in the output. |
isSparse | Should the output be a sparse array? |
Remarks
- Introduced in MATLAB v7.0.
References:
- "Under-appreciated
accumarray", by Loren Shure, February 20, 2008. accumarrayin the official MATLAB documentation.
