为具有 1 个值或 0 的列表的列表计算 st.dev 和均值

Question

我有这个列表列表：

fall_2_gpa = [[4.0, 3.4175, 3.1675, 3.2475, 3.25, 3.2475, 3.3325, 3.585, 3.5825, 3.3325, 3.5, 3.585, 3.8325, 3.165, 3.5025, 3.835, 3.5, 3.4175, 3.6675, 3.165, 3.25, 3.4175, 3.9175, 3.6675, 3.8325, 3.2475, 3.4175, 3.4175, 3.5825, 3.415, 3.5825, 3.585, 3.25, 3.4175, 3.6675, 3.3325, 3.5, 3.165, 3.3325, 3.6675, 3.6675], [3.5], [3.1675, 3.4175, 3.5, 3.6675, 2.5, 2.835, 3.585, 3.4175, 3.25, 3.4175, 3.1675, 3.75], [2.6675, 3.0], [3.0825, 3.665, 3.6675, 3.3325, 3.3325, 3.415], [3.3325, 3.415, 3.415, 3.415, 3.75, 3.75, 3.665, 3.6675, 3.6675, 3.5825, 3.5825, 3.9175, 3.4175, 3.6675, 3.5, 3.5825, 3.585, 3.6675, 3.665, 3.4175, 3.585, 3.4175, 3.415, 3.75, 4.0, 3.5, 3.6675, 3.25, 3.585, 3.3325, 3.4175, 3.5, 3.6675, 3.7525, 3.3325, 3.835, 3.335, 3.665, 3.5, 3.6675, 3.585, 3.75, 3.75, 3.5, 3.415, 3.0825, 3.6675, 3.2475, 3.2475, 3.335, 3.9175, 3.75, 3.75, 3.75, 3.585, 3.585, 3.4175, 3.25, 3.3325, 3.5, 3.25, 3.75, 2.835, 3.1675, 2.5825, 3.25, 3.5825, 2.915, 2.8325, 2.5, 3.0825, 3.3325, 2.8325, 3.25, 2.8325, 3.335], [3.5, 3.3325, 3.6675], [3.165, 3.4175, 3.4975, 3.25], [3.5825, 3.5, 3.4175, 3.75, 3.335, 3.335, 3.415, 3.5, 3.6675, 3.165, 3.6675, 3.4975, 3.9175, 3.6675, 3.4175, 3.25, 3.3325, 3.585, 3.835, 3.2475, 3.335, 3.75, 3.5825, 3.5, 3.4175, 3.5, 3.75, 3.5825, 3.585, 3.335, 3.5825, 3.5825, 3.3325, 3.75, 3.5, 3.6675, 3.3325, 3.5825, 3.4175, 3.415, 3.585, 3.75, 3.415, 3.4175, 3.25, 3.4175, 3.415, 3.415, 3.75, 3.9175, 3.8325, 3

mean_fall_2 = [statistics.mean(d) for d in fall_2_gpa if d != 0]
stdev_fall_2 = [statistics.stdev(d) for d in fall_2_gpa if d != 0]

但我不断收到此错误：

statistics.StatisticsError：方差至少需要两个数据点

我相信我得到这个是因为一些子列表只有 1 个值并且不超过 2 个。对于另一个列表我得到这个错误：

statistics.StatisticsError: mean 至少需要一个数据点

这可能意味着它找到了一个空的子列表？

有办法解决这些问题吗？我需要 st.dev 并且意味着要计算所有内容，无一例外。

Answer 1

fall_2_gpa 列表包含一些大小为 1 的列表，这些列表将传递给 statistics.stdev() 函数。但是，statistics.stdev() 期望参数至少有两个项目。因此，我们可以在处理列表项时添加一个条件来检查列表的大小：-stdev_fall_2 = [statistics.stdev(d) for d in fall_2_gpa if d != 0 and len(d)>1]以类似的方式，我们也可以指示函数在列表大小小于 2 时使用一些默认值。使用以下内容在 else 条件下添加 0：stdev_fall_2 = [statistics.stdev(d) if d != 0 and len(d) > 1 else 0 for d in fall_2_gpa]