Operation reduce

stream.Reduce

It reduces the stream to a single value by executing a provided function for each value of the stream.

Signature

func (s stream.Stream) Map(fn func{interface{},interface{}}interfac€{}) (out *stream.Output)

Arguments

Name	Type	Description
fn	func	This function must receive two arguments, the first argument is an accumulator and the second a element of the same type that the elements in the stream. The output of this function will have the same type than the accumulator

Output

Name	Type	Description
out	*stream.Output	It's a pointer to the below structure

type Output struct {
  value reflect.Value
  error *errors.Error
}

Errors

Type	Description
err.items-nil	The stream is nil
err.invalid-argument	The reduce operation requires a function as argument
err.invalid-argument	The provided function must retrieve 2 arguments
err.invalid-argument	The provided function must return 1 value
err.invalid-argument	The type of the second argument in the provided function must be the same of the elements in the stream
err.invalid-argument	The type of the first argument and the output in the provided function must be the same

Example

package main

import (
	"fmt"
	"github.com/wesovilabs/koazee"
)

var stream = koazee.StreamOf([]int{1, 2, 3, 4, 5})

func main() {
	out := stream.Reduce(func(acc, val int) int { return acc + val })
	fmt.Println(out.Int())
}

Download

Benchmark

Sum the len of all the string elements in a tream

Test Identifier	Stream Len	Speed
BenchmarkReduceString10SumLen-4	10	355 ns/op
BenchmarkReduceString100SumLen-4	100	723 ns/op
BenchmarkReduceString1000SumLen-4	1000	4254 ns/op
BenchmarkReduceString5000SumLen-4	5000	21286 ns/op

Sum all the elments in a stream of ints

Test Identifier	Stream Len	Speed
BenchmarkReduceInt10Sum-4	10	324 ns/op
BenchmarkReduceInt100Sum-4	199	629 ns/op
BenchmarkReduceInt1000Sum-4	1999	3782 ns/op
BenchmarkReduceInt5000Sum-4	5000	9533 ns/op

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