hasnext

Determine if ValueIterator has one or more values available

Syntax

tf = hasnext(ValIter)

Description

tf = hasnext(ValIter) returns logical 1 (true) if ValueIter has one or more values available; otherwise, it returns logical 0 (false).

Examples

Get Values from ValueIterator in Reduce Function

Use the hasnext and getnext functions in a while loop within the reduce function to iteratively get values from the ValueIterator object. For example,

function MeanDistReduceFun(sumLenKey, sumLenIter, outKVStore)
    sumLen = [0 0];
    while hasnext(sumLenIter)
        sumLen = sumLen + getnext(sumLenIter);
    end
    add(outKVStore, 'Mean', sumLen(1)/sumLen(2));
end

Always call hasnext before getnext to confirm availability of a value. mapreduce returns an error if you call getnext with no remaining values in the ValueIterator object.

Input Arguments

ValIter — Intermediate value iterator

ValueIterator object

Intermediate value iterator, specified as a ValueIterator object. The mapreduce function automatically creates this object during execution. The second input to the reduce function specifies the variable name for the ValueIterator object, which is the variable name to use with the hasnext and getnext functions.

For more information, see ValueIterator.

Version History

Introduced in R2014b