我有以下运动方程式
move = target_position - position
position = position + move
其中target_position是一个流,并且位置初始化为零。我希望有一个职位。我已经尝试过这样的事情(在rx伪代码中)
moves = Subject()
position = moves.scan(sum,0)
target_position.combine_latest(position,diff).subscribe( moves.on_next)
它有效,但我已阅读应避免使用Subject。是否可以在没有主题的情况下计算位置流?
在python中,完整的实现如下所示
from pprint import pprint
from rx.subjects import Subject
target_position = Subject()
moves = Subject()
position = moves.scan(lambda x,y: x+y,0.0)
target_position\
.combine_latest(position,compute_next_move)\
.filter(lambda x: abs(x)>0)\
.subscribe( moves.on_next)
position.subscribe( lambda x: pprint("position is now %s"%x))
moves.on_next(0.0)
target_position.on_next(2.0)
target_position.on_next(3.0)
target_position.on_next(4.0)
最佳答案
您可以使用expand operator
targetPosition.combineLatest(position, (target, current) => [target, current])
.expand(([target, current]) => {
// if you've reached your target, stop
if(target === current) {
return Observable.empty()
}
// otherwise, calculate the new position, emit it
// and pump it back into `expand`
let newPosition = calcPosition(target, current);
return Observable.just(newPosition)
})
.subscribe(updateThings);