arrays - Swift:调用函数时调用 EXC_BAD_INSTRUCTION

Question

所以我试图让标准差函数起作用，但是我遇到了错误。这是我的代码:

func standardDeviation(dataSet: [Double]) -> Double {
let mean = dataSet.reduce(0, +) / Double(dataSet.count)
var distances = [Double]()
for number in dataSet {
    let distanceFromMean = (dataSet[Int(number)] - mean)
    distances.append(distanceFromMean * distanceFromMean)
}

return distances.reduce(0, +) / Double(dataSet.count)
}

它输出以下错误:

Fatal Error: Index out of range

所以，我有一种感觉，当我调用 dataSet 数组时，这是要做的事情，所以当我研究它时，我发现这是一个错误

error: Execution was interrupted, reason: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0). The process has been left at the point where it was interrupted, use "thread return -x" to return to the state before expression evaluation.

Answer 1

number(Double!)不能作为订阅dataSet的索引，所以我很确定您的意思/em>

let distanceFromMean = number - mean

在快速枚举模式中，索引变量number实际上等于array[index]