Python 熊猫获得两列的最小值作为等式的一部分
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pandas get minimum value of two columns as part of an equation
提问by kilojoules
How can I reference the minimum value of two dataframes as part of a pandas dataframe equation? I tried using the python min()function which did not work. I'm sorry if this is well-documented somewhere but I have not been able to find a working solution for this problem. I am looking for something along the lines of this:
如何将两个数据帧的最小值作为熊猫数据帧方程的一部分？我尝试使用min()不起作用的python函数。如果这在某处有详细记录，我很抱歉，但我无法找到解决此问题的有效解决方案。我正在寻找类似的东西：
data['eff'] = pd.DataFrame([data['flow_h'], data['flow_c']]).min() *Cp* (data[' Thi'] - data[' Tci'])
I also tried to use pandas min()function, which is also not working.
我也尝试使用 pandasmin()函数，这也不起作用。
min_flow = pd.DataFrame([data['flow_h'], data['flow_c']]).min()
InvalidIndexError: Reindexing only valid with uniquely valued Index objects
I was confused by this error. The data columns are just numbers and a name, I wasn't sure where the index comes into play.
我对这个错误感到困惑。数据列只是数字和名称，我不确定索引在哪里起作用。
In [108]: data['flow_c']
Out[108]:
0 74.014640
1 74.150579
2 74.014640
3 73.960195
4 74.069046
5 73.960195
6 73.987423
7 73.905710
采纳答案by Happy001
Your question is not very clear to me, but my guess is that you are trying to get element-wise mininumof two Series(not DataFrames). If that's what you want, try: data[['flow_h','flow_c']].min(axis=1).
你的问题对我来说不是很清楚，但我的猜测是你正试图获得mininum两个Series（不是DataFrames）的元素。如果这是你想要的东西，尝试：data[['flow_h','flow_c']].min(axis=1)。
回答by b0lle b
If you like to get a single minimum value of multiple columns:
如果您想获得多列的单个最小值：
data[['flow_h','flow_c']].min().min()
the first "min()" calculates the minimum per column and returns a pandas series. The second "min" returns the minimum of the minimums per column.
第一个“min()”计算每列的最小值并返回一个熊猫系列。第二个“min”返回每列最小值中的最小值。
