How to round average in Java stream?

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I want to calculate the average of a list of integers and then round the result to half up (i.e. >= .5 is rounded to nearest integer up and < .5 is rounded to the nearest integer down). How do I do this with Java stream ?

public static void main(String [] args){
    List<Integer> values = new ArrayList<>();
    values.add(60);
    values.add(30);
    values.add(20);

    double avg = values.stream().mapToInt(a -> a).average().getAsDouble();

    System.out.println(avg);
}

I was hoping for something like

...average().round(RoundingMode.HALF_UP).getAsInt();

Your intent is to round the result, not values within the stream itself. So just wait until you have the double, then round that value with Math.round() by replacing this:

System.out.println(avg);
// output: 36.666666666666664

with this:

System.out.println(Math.round(avg));
// output: 37

How to average BigDecimals using Streams?, BigDecimal[] totalWithCount = bigDecimals.stream() .filter(bd -> bd != null) .map(​bd It is up to you how to round the divided value though (I use RoundingMode. DoubleStreamLogicBig. Method: OptionalDouble average() This terminal operation returns an OptionalDoubledescribing the arithmetic mean of elements of this stream, or an empty optional if this stream is empty. This is a special case of reduction. If any element is a NaN or the sum is at any point a NaN then the average will be NaN. Examples. package com.logicbig.example.doublestream;import java.util.stream.DoubleStream;public class AverageExample {public static void main(String args)

This would work Java 9 onward;

double avg = values.stream().mapToInt(Integer::intValue)
                .average()
                .stream()
                .map(Math::round)
                .findFirst()
                .orElse(0);

Java 8 Streams - DoubleStream.average Examples, Method: OptionalDouble average(). This terminal operation returns an OptionalDouble describing the arithmetic mean of elements of this stream, or an empty  IntStream average() in Java with Examples java.util.stream.IntStream in Java 8, deals with primitive ints. It helps to solve the old problems like finding maximum value in array, finding minimum value in array, sum of all elements in array, and average of all values in array in a new way.

what about rounding that double??

avg = Math.round(avg);
System.out.println(avg);

Average of a stream of numbers, The average after including x number can be written as (prev_avg*n + x)/(n+1). C​++; Java; Python3; C#; PHP. C++. Average Using the Java Stream API public static double findAverageUsingStream(int[] array) { return Arrays.stream(array).average().orElse(Double.NaN); } IntStream.average() returns an OptionalDouble which may not contain a value and which needs a special handling.

DoubleStream average() in Java with Examples, java.util.stream.DoubleStream in Java 8, deals with primitive doubles. It helps to solve the old problems like finding maximum value in array, finding minimum  I have implemented function that gets average weight value using Java 8 features: public float getAvgChangedWeight() { return (float) weightChanges.stream().mapToDouble(WeightChange::getValue).average().getAsDouble(); }

Java 9 Cookbook: Solutions for Modular, Functional, Reactive, and , First, let's implement the if block (that calculates the average speed of less than + speed); return (double) Math.round(speed); We get the trafficUnitsNumber of it seems that Java follows the general trend of more fluent and stream-like style,  An average of a set of numbers is their sum divided by their quantity. It can be defined as − average = sum of all values / number of values. Here we shall learn how to programmatically calculate average. Algorithm 1. Collect integer values in an array A of size N. 2. Add all values of A. 3. Divide the output of Step 2 with N. 4.

Find Sum and Average in a Java Array, In this quick tutorial, we'll cover how we can calculate sum & average in an array using both Java standard loops and the Stream API. After refreshing our basic understanding let’s get into details of how Java deals with rounding. 3. Rounding Method in Java. The Java language provides a static round method from the java.lang.Math class.

Comments
  • IntStream.of(60, 30, 20).average().stream().map(Math::round).findFirst().getAsDouble();
  • Thats what I ended up doing/