除了Python中的一些值之外，如何获取排序数组的索引？

def binary_search(arr, target):
    left = 0
    right = len(arr) - 1

    while left <= right:
        mid = (left + right) // 2
        if arr[mid] == target:
            return mid
        elif arr[mid] < target:
            left = mid + 1
        else:
            right = mid - 1

    return -1  # 目标值不存在

arr = [1, 2, 3, 4, 5, 6, 7, 8, 9]
target = 6
index = binary_search(arr, target)
print("目标值的索引为:", index)