测向平均值这不是这个系列的真正意义吗？

Question

我正在调试并遇到以下奇怪的行为。 我在计算一个熊猫系列的平均数，这个系列包含了完全相同的数字。但是，pd.mean()给出了一个不同的数字。你知道吗

问题1：为什么这个系列的平均数是一个不同的数字？你知道吗

问题2：tmm[-1]== tmm.mean()现在给出False。有什么办法可以忽略这个微小的差别，让结果变成真实的吗？我不喜欢abs(tmm[-1]-tmm.mean()) < xxx

方法，因为不确定如何定义xxx。你知道吗

import pandas as pd
import decimal

tmm = pd.Series(14.9199999999999999289457264239899814128875732421875,
                index=range(30))
for t in tmm:
    print(decimal.Decimal(t))
print('mean is')
print(decimal.Decimal(tmm.mean()))

结果：

14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
14.9199999999999999289457264239899814128875732421875
mean is
14.9200000000000034816594052244909107685089111328125

Answer 1

你的两个问题的答案基本上是这样的：

import pandas as pd
import decimal

tmm = pd.Series(decimal.Decimal(14.9199999999999999289457264239899814128875732421875),
                index=range(30))
for t in tmm:
    print(decimal.Decimal(t))
print('mean is')
print(decimal.Decimal(tmm.mean()))

一定要使用十进制。十进制当你创建tmm的时候，这是非常重要的。你知道吗

Answer 2

尝试使用np.isclose()

tmm[20]== tmm.mean()

False

np.isclose(tmm[20], tmm.mean())
True