比较列表并返回新列表

Question

嗨，我正在尝试对我的函数进行编程，该函数采用一个嵌套列表，一个数字选择哪个行，然后一个特定的数字。因此，其假设要做的是接收3个参数height_map（一个嵌套列表），map_row（选择行）和level（一个int）。并返回特定行小于，等于和大于级别的次数。

到目前为止，我知道如何在嵌套列表中选择特定的行，但是当我尝试使其嵌套时，它将返回3的列表，但似乎没有作用

示例是compare_elevations_within_row（THREE_BY_THREE，1，5），THREE_BY_THREE = [[1、2、1]，[4、6、5]，[7、8、9]并返回[1,1,1]

def compare_elevations_within_row(elevation_map: List[List[int]], map_row: int,
                                  level: int) -> List[int]:
    """Return a new list containing the three counts: the number of
    elevations from row number map_row of elevation map elevation_map
    that are less than, equal to, and greater than elevation level.

    >>> compare_elevations_within_row(THREE_BY_THREE, 1, 5)
    [1, 1, 1]
    THREE_BY_THREE = [[1, 2, 1],
                  [4, 6, 5],
                  [7, 8, 9]]


    """
    num = elevation_map[map_row]
    count = []
    for index in num:
        if index < level:
            count[0] = count + 1
        elif index== level:
            count[1] = count + 1
        else:
            count[2] = count + 1
    return count

Answer 1

有一些小问题：

• [count应该用三个零（A）初始化
• 当给定count索引处的值增加时，应基于该索引处的当前值（B）为基础

考虑：

def compare_elevations_within_row(elevation_map: List[List[int]], map_row: int,
                                  level: int) -> List[int]:
    """Return a new list containing the three counts: the number of
    elevations from row number map_row of elevation map elevation_map
    that are less than, equal to, and greater than elevation level.

    >>> compare_elevations_within_row(THREE_BY_THREE, 1, 5)
    [1, 1, 1]
    THREE_BY_THREE = [[1, 2, 1],
                  [4, 6, 5],
                  [7, 8, 9]]


    """
    count = [0] * 3             # (A)
    for value in elevation_map[map_row]:
        if value < level:
            count[0] += 1       # (B)
        elif value == level:
            count[1] += 1       # (B)
        else:
            count[2] += 1       # (B)
    return count

是您的代码最接近的工作版本。您还可以探索并考虑使用collections.namedtuple类或dataclass模块作为返回值，而不是“原始”三元素列表。