累积值，例如扫描，但可以随着时间的推移重置累加器 [英] accumulating values such as with scan but with the possibility to reset the accumulator over time

问题描述

我有一个 Observable，obs1，它代表随着时间推移的一系列数字.我需要累加这些数字的总和并逐步发出它(即说我需要使用 scan 运算符很长的路要走).

I have one Observable, obs1, which represents a stream of numbers over time. I need to accumulate the sum of such numbers and emit it progressively (i.e. a long way to say I need to use scan operator).

然后是第二个 Observable，obs2，代表某种重置时间".换句话说，当 obs2 发出时，我必须重置我在 obs1 上设置的累加器并从 0 开始求和.

Then there is a second Observable, obs2, that represents some sort of "reset time". In other words, when obs2 emits, I have to reset the accumulator I have set on obs1 and start summing from 0.

我想我已经能够通过以下代码达到我想要的行为，但我不确定这是正确的方法(对我来说有点味道)

I think I have been able to reach the behavior I want with the following code, but I am not sure it is the right way to do it (it sorts of smells to me)

const obs1 = Observable.interval(100).mapTo(1).take(100);

const obs2 = Observable.interval(700).take(10);

obs1.pipe(
    windowWhen(() => obs2),
    mergeMap(d => d.pipe(scan((acc, one) => acc + one, 0)))
)
.subscribe(console.log);

有什么改进的建议吗?

推荐答案

大概这就是我要找的东西

Probably something like this is what i was looking for

const obs1 = Observable.interval(100).mapTo(1).take(100);

const obs2 = Observable.interval(700).take(10);


function scanReset(seed) {
    return obs1.pipe(
        scan((acc, one) => acc + one, seed)
    )
}

obs2.pipe(
    switchMap(() => scanReset(0))
)
.subscribe(console.log);

这篇关于累积值，例如扫描，但可以随着时间的推移重置累加器的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！