flatmap Questions
1
Solved
Given the following piece of code
public static void main(String[] args) {
long start = System.currentTimeMillis();
Flux.<Long>generate(s -> s.next(System.currentTimeMillis() - start)...
Zashin asked 4/11, 2017 at 7:32
3
How I can merge List<Map<String,String>> to Map<String,String> using flatMap?
Here's what I've tried:
final Map<String, String> result = response
.stream()
.collect(Coll...
1
Solved
I can't figure out how the Scala compiler figures out how to use flatMap with a sequence of Options.
If I use a flatMap on a sequence of sequences:
println(Seq(Seq(1), Seq()).flatMap(a => a)) ...
Schoening asked 8/10, 2017 at 10:34
3
Solved
scala> List(List(1), List(2), List(3), List(4))
res18: List[List[Int]] = List(List(1), List(2), List(3), List(4))
scala> res18.flatten
res19: List[Int] = List(1, 2, 3, 4)
scala> res18.fl...
Letti asked 18/11, 2014 at 22:14
2
Solved
Consider the following code:
typealias PersonRecord = [String : AnyObject]
struct Person {
let name: String
let age: Int
public init(name: String, age: Int) {
self.name = name
self.age = ag...
1
Solved
Can someone explain to me why the .flatMap operator can accept a function which returns an Observable, or an array?
The official docs say:
The FlatMap operator transforms an Observable by apply...
Gaut asked 22/7, 2017 at 23:59
4
Solved
In Swift, I am trying to flatten an array of dictionaries into one dictionary
i.e
let arrayOfDictionaries = [["key1": "value1"], ["key2": "value2"], ["key3": "value3", "key4": "value4"]]
//the e...
Willawillabella asked 24/2, 2016 at 9:15
1
Solved
flatten Vs flatMap with def method and val function:
I defined a def method called toInt:
def toInt(s: String): Option[Int] = {
try {
Some(Integer.parseInt(s.trim))
} catch {
case e: Excepti...
2
Solved
How can I convert a Set<Result> into a Map<Item, Set<String>> or SetMultimap<Item, String> using Java 8 streams or Multimaps, where Result is:
class Result {
String name;
...
Father asked 6/4, 2017 at 4:7
1
Swift documentation of flatMap reads:
Returns an array containing the non-nil results of calling the given
transformation with each element of this sequence.
In the following examples when r...
Riyal asked 13/2, 2017 at 22:41
1
Solved
Given the following as an example of data classes:
class Country {
List<Region> regions = new ArrayList<>();
List<Region> getRegions() {
return regions;
}
}
class Region ...
Paperback asked 9/2, 2017 at 16:52
1
Solved
This is a follow-up to this question:
flatMap and `Ambiguous reference to member` error
There I am using the following code to convert an array of Records to an array of Persons:
let records = /...
3
Solved
I'm trying to use flatmap to make a nested loop with the Stream API, but I can't seem to figure it out. As an example, I want to recreate the following loop:
List<String> xs = Arrays.asList(...
Experimentation asked 18/11, 2016 at 13:55
4
Solved
I have an array of Bools and want to edit an array of Scores and an array of Dates for the values that are False. I can't get to it. I thought of getting elements that are false and using that arra...
2
Solved
I am trying to create all possible pairs of items in a FlatMap:
possible_children.clone().flat_map(|a| possible_children.clone().map(|b| (a,b)))
In order to do this, I am trying to clone a FlatM...
1
Solved
2
Solved
let arr: [Int?] = [1,2,3,4,nil]
let arr1 = arr.flatMap { next in
next
}
// arr1: [1,2,3,4]
let arr2: [Int?] = arr.flatMap { next -> Int? in
next
}
// arr2: [Optional(1), Optional(2), Optional...
Electrometer asked 29/5, 2016 at 3:10
2
Solved
I'm reading the Learning Spark book and couldn't understand the following pair rdd transformation.
rdd.flatMapValues(x => (x to 5))
It is applied on an rdd {(1,2),(3,4),(3,6)} and the output ...
Floatage asked 18/5, 2016 at 14:14
1
Solved
I'm using Jupyter Notebook with PySpark. Within that I have a have a dataframe that has a schema with column names and types (integer, ...) for those columns. Now I use methods like flatMap but thi...
Mehala asked 14/5, 2016 at 9:59
5
Solved
If I use xxx.flatMap(_.split(" ")), will it split the array an then flatten or will it flatten and then split?
2
Solved
For example,
Vector(Some(1), Some(2), Some(3), None).flatMap{
n => n
}
produces a Vector(1, 2, 3) instead of giving an error. As I have seen in other languages, flatMap is used when you have...
Themselves asked 12/1, 2016 at 4:2
5
Solved
I have been looking into FP languages (off and on) for some time and have played with Scala, Haskell, F#, and some others. I like what I see and understand some of the fundamental concepts of FP (w...
Solitary asked 12/12, 2015 at 0:19
2
Solved
// given a set of Item objects, group them by the managers of creator and owners
Map<String, List<Item>> managersItems =
itemSet.parallelStream().flatMap(item -> {
// get the list...
Rowan asked 12/10, 2015 at 23:47
2
Solved
I expected to be able to use Stream::flatMap like this
public static List<String> duplicate(String s) {
List<String> l = new ArrayList<String>();
l.add(s);
l.add(s);
return...
Toreutic asked 11/9, 2015 at 8:11
1
Solved
My goal is exactly what the title say. What I'm doing is:
.stream().flatMap(x -> x.getTitles())
getTitles() returns a LinkedList<String>, and I expected flatMap() to do the job and cre...
Yearly asked 22/6, 2015 at 20:7
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