reduce

Java 8 Stream - Reduce function's combiner not getting executed [duplicate]

由 一曲冷凌霜 提交于 2020-01-10 04:35:21
问题 This question already has answers here : Java8 stream.reduce() with 3 parameters - getting transparency (2 answers) Closed 3 years ago . I am using a simple reduce method with three arguments viz. identity, accumulator and combiner. Here is my code... Integer ageSumComb = persons .stream() .reduce(0, (sum, p) -> { System.out.println("Accumulator: Sum= "+ sum + " Person= " + p); return sum += p.age; }, (sum1, sum2) -> { System.out.format("Combiner: Sum1= " + sum1 + " Sum2= "+ sum2); return

codeWars in action（2014-05-06）

由 假如想象 提交于 2020-01-08 13:19:35
【推荐】2019 Java 开发者跳槽指南.pdf(吐血整理) >>> 一、 Description: Write a small function that returns the values of an array that are not odd. All values in the array will be integers. Return the good values in the order they are given . my solution: function noOdds(values) { var arr = []; values.filter(function (val) { if (val % 2 === 0) { arr.push(val); } }); console.log(arr); return arr; } solution from web: function no_odds( values ){ // Return all non-odd values return values.filter(function(val){return val%2===0}) } 二、 Description: Fellow code warrior, we need your help! We seem to have lost one of

MapReduce outputs lines from input file besides the expected result

由 落爺英雄遲暮 提交于 2020-01-06 11:04:11
问题 I managed to implement a Map-Reduce in Java, it works for my case but for some reason the output displays besides the desired one, some data from the input file and I can't figure out why? Here is the class, I left a comment in code to the line which cause me problems. If I delete that line it doesn't work anymore, but with that line written I have that awkward output(containing data for my input + the desired output) The problem is in "reduce" method at the bottom - I left a comment there

How to reduce App's CPU usage in Android phone?

由 落爺英雄遲暮 提交于 2020-01-03 02:14:13
问题 I developed an auto-call application. The app reads a text file that includes a phone number list and calls for a few second, ends the call and then repeats. My problem is that the app does not send calls after 10~16 hours. I don't know the reason exactly, but I guess that the problem is the CPU usage. My app's CPU usage is almost 50%! How do I reduce CPU usage? Here is part of source code: if(r_count.compareTo("0")!=0) { while(index < repeat_count) { count = 1; time_count = 2; while(count <

How to reduce App's CPU usage in Android phone?

由 倖福魔咒の 提交于 2020-01-03 02:14:07
问题 I developed an auto-call application. The app reads a text file that includes a phone number list and calls for a few second, ends the call and then repeats. My problem is that the app does not send calls after 10~16 hours. I don't know the reason exactly, but I guess that the problem is the CPU usage. My app's CPU usage is almost 50%! How do I reduce CPU usage? Here is part of source code: if(r_count.compareTo("0")!=0) { while(index < repeat_count) { count = 1; time_count = 2; while(count <

Swift: Reduce Function with a closure

由 南笙酒味 提交于 2020-01-02 07:52:56
问题 Below is the code that I'm struggling to understand: let rectToDisplay = self.treasures.reduce(MKMapRectNull) { //1 (mapRect: MKMapRect, treasure: Treasure) -> MKMapRect in //2 let treasurePointRect = MKMapRect(origin: treasure.location.mapPoint, size: MKMapSize(width: 0, height: 0)) //3 return MKMapRectUnion(mapRect, treasurePointRect) } My understanding of reduce function is: var people [] // an array of objects var ageSum = 0 ageSum = people.reduce(0) { $0 + $1.age} //(0) = initial value /

reduce() vs. fold() in Apache Spark

由 不问归期 提交于 2020-01-01 09:54:07
问题 What is the difference between reduce vs. fold with respect to their technical implementation? I understand that they differ by their signature as fold accepts additional parameter (i.e. initial value) which gets added to each partition output. Can someone tell about use case for these two actions? Which would perform better in which scenario consider 0 is used for fold ? Thanks in advance. 回答1: There is no practical difference when it comes to performance whatsoever: RDD.fold action is using

What is the difference between combining array by using reduce or joined?

由 依然范特西╮ 提交于 2019-12-31 00:56:09
问题 Consider the following array -of strings-: let arrayStrings = ["H", "e", "l", "l", "o"] For combining its elements (to get "Hello" as single String), we could: reduce it: let reducedString = arrayStrings.reduce("", { $0 + $1 }) // "Hello" Or join it: let joinedString = arrayStrings.joined() // "Hello" Both would return "Hello" String as output. However, what is the logic to keep in mind to determine what is the better choice for such a process? What is the difference when comparing based on

What is the difference between combining array by using reduce or joined?

由 ↘锁芯ラ 提交于 2019-12-31 00:55:59
问题 Consider the following array -of strings-: let arrayStrings = ["H", "e", "l", "l", "o"] For combining its elements (to get "Hello" as single String), we could: reduce it: let reducedString = arrayStrings.reduce("", { $0 + $1 }) // "Hello" Or join it: let joinedString = arrayStrings.joined() // "Hello" Both would return "Hello" String as output. However, what is the logic to keep in mind to determine what is the better choice for such a process? What is the difference when comparing based on

Count the number of true members in an array of boolean values

由 时光怂恿深爱的人放手 提交于 2019-12-30 03:48:06
问题 New to javascript and I'm having trouble counting the number of trues in an array of boolean values. I'm trying to use the reduce() function. Can someone tell me what I'm doing wrong? //trying to count the number of true in an array myCount = [false,false,true,false,true].reduce(function(a,b){ return b?a++:a; },0); alert("myCount ="+ myCount); // this is always 0 回答1: Seems like your problem is solved already, but there are plenty of easier methods to do it. Array.prototype.filter() - the
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