尝试创建类型为MovingAvarage的切片

Question

I am using the RobinUS2/golang-moving-average library to compute moving avarages, but I am unable to assembe a slice of these avarages to compute MA for multiple variables.

ma := []movingaverage.MovingAverage{}
    ma[0] = movingaverage.New(15)
    ma[0].Add(3.14)

What could be wrong? I get an index out of range error. Thanks!

Answer 1

You need to either pre-size the slice with

ma := make(movingaverage.MovingAverage, 5)

Which gives a slice of capacity 5 and length 5 with each entry set to the zero value

Better though to initialise it as you did but then to add new entries with

ma = append(ma, movingaverage.New(15)) 

If you know how big your eventual slice will be you can pre-allocate the underlying array with

ma := make(movingaverage.MovingAverage, 0, 5)

which will give you a slice of length 0 but capacity 5 so you don't have to do repeated memory allocations and moves