 Scala: What is the difference between filter and takeWhile on a stream?
By : Manisha Rathore
Date : March 29 2020, 07:55 AM
it fixes the issue The difference isn't stream-specific, but the same for all collections extending GenTraversableLike: filter code :
> List(1, 2, 3, 4).filter(_ % 2 == 1)
List(1, 3)
> List(1, 2, 3, 4).takeWhile(_ % 2 == 1)
List(1)
|
 filter vs takeWhile: difference and runtime
By : Nivedita22
Date : March 29 2020, 07:55 AM
I hope this helps you . Yes there is a huge difference. If we read the documentation, we see: code :
filter odd (map (^2) [1..])
Prelude> takeWhile odd [1,3,5,12,7,9,1,3]
[1,3,5]
Prelude> filter odd [1,3,5,12,7,9,1,3]
[1,3,5,7,9,1,3]
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 RxJs 6 - React to concatMap in filter or takeWhile condition
By : jitender chauhan
Date : March 29 2020, 07:55 AM
it should still fix some issue The last callback of your subscribe is ran only for the second call. If you want the first HTTP call to call a method once done, try this : code :
this.myService.createArticle(article)
.pipe(
finalize(() => console.log('Finally I have really reached the END (of the first call)'))
filter(() => this.checkbox),
concatMap(() => return this.mailer.createOtherResource(data)),
}).subscribe(
(x) => { console.log('OK', x); },
error => console.error('FALLA', error),
() => console.log('Finally I have really reached the END')
);
|
 Why takeWhile operator doesn't filter when inclusive?
By : user3219176
Date : March 29 2020, 07:55 AM
wish helps you After digging a little with the source code of the operator ( https://github.com/ReactiveX/rxjs/blob/master/src/internal/operators/takeWhile.ts), there is indeed something wrong I gonna report as an issue to github. in the meantime, here is a fixed custom takeWhileInclusive operator code :
import { from, BehaviorSubject, Observable } from 'rxjs';
import { map, takeWhile } from 'rxjs/operators';
/** Custom takewhile inclusive Custom takewhile inclusive properly implemented */
const customTakeWhileInclusive = <T>(predicate: (value: T) => boolean) => (source: Observable<T>) => new Observable<T>(observer => {
let lastMatch: T | undefined // fix
return source.subscribe({
next: e => {
if (lastMatch) {
observer.complete();
}
else {
if (predicate(e)) {
/*
* Code from https://github.com/ReactiveX/rxjs/blob/master/src/internal/operators/takeWhile.ts
*
* if (this.inclusive) {
* destination.next(value); // NO! with a synchronous scheduler, it will trigger another iteration without reaching the next "complete" statement
* and there is no way to detect if a match already occured!
* }
* destination.complete();
*/
// Fix:
lastMatch = e; // prevents from having stackoverflow issue here
}
observer.next(e);
}
},
error: (e) => observer.error(e),
complete: () => observer.complete()
});
});
const value$ = new BehaviorSubject<number>(1);
const source = value$.pipe(
map(x => `value\$ = ${x}`),
//takeWhile(x => !x.includes('4'), true)
customTakeWhileInclusive(x => x.includes('4')) // fix
);
source.subscribe(x => {
console.log(x);
value$.next(4);
});
|
 Difference between takeWhile() and filter() method in Kotlin
By : JavaJack
Date : March 29 2020, 07:55 AM
To fix this issue The difference between both is filter() method returns a list with the elements that match an specific condition. And takeWhile() method also returns a list with the elements that match with the specific condition but just taking in account the firsts elements on the list.
An example for that:
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» 
code :
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