在pandas DataFrame中设置最大值(上限) [英] Set maximum value (upper bound) in pandas DataFrame

问题描述

我正在尝试设置pandas DataFrame列的最大值.例如:

I'm trying to set a maximum value of a pandas DataFrame column. For example:

my_dict = {'a':[10,12,15,17,19,20]}
df = pd.DataFrame(my_dict)

df['a'].set_max(15)

将产生产量:

    a
0   10
1   12
2   15
3   15
4   15
5   15

但事实并非如此.

有一百万种解决方案，以找到最大值，但没有任何办法设置最大值……至少我能找到.

There are a million solutions to find the maximum value, but nothing to set the maximum value... at least that I can find.

我可以遍历列表，但是我怀疑有一种更快的方法可以处理大熊猫.我的列表将明显更长，因此我希望迭代花费相对较长的时间.另外，我希望能够使用NaN的任何解决方案.

I could iterate through the list, but I suspect there is a faster way to do it with pandas. My lists will be significantly longer and thus I would expect iteration to take relatively longer amount of time. Also, I'd like whatever solution to be able to handle NaN.

推荐答案

我想您可以做到:

maxVal = 15
df['a'].where(df['a'] <= maxVal, maxVal)      # where replace values with other when the 
                                              # condition is not satisfied

#0    10
#1    12
#2    15
#3    15
#4    15
#5    15
#Name: a, dtype: int64

或者:

df['a'][df['a'] >= maxVal] = maxVal

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