A calculator to return the average of the last number of x items. This can be useful when you want to estimate time remaining.

MovingAverage.ps1

# Converted from this answer: https://stackoverflow.com/a/44318312/1277533

class AverageCalculator {
    [System.Collections.Queue]$Queue
    [long]$Total
    [int]$Size

    AverageCalculator([int]$Size) {
        $this.Queue = New-Object System.Collections.Queue
        $this.Size = [Math]::Max($Size, 1)
    }

    [int]CalculateAverage($num) {
        $this.Total += $num
        $this.Queue.Enqueue($num)
        if($this.Queue.Count -gt $this.Size) {
            $this.Total -= $this.Queue.Dequeue()
        }
        $average = $this.Total / $this.Queue.Count
        return $average
    }
}

$calculator = New-Object AverageCalculator 7
1..1000 | % {
    
    $num = Get-Random -Minimum 0 -Maximum 4
    $average = $calculator.CalculateAverage($num)
    $left = $average * (1000 - $_)
    Write-Host $left
}