如何对 dataframe 中的列进行排序，使第一行中的值从大到小？

Question

I have the following dataframe:

	Audi	Hyundai	Kia	Mercedes	Tesla	VW	Volvo
2019	0.25	nan	nan	0.5	nan	nan	0.25
2020	nan	0.125	nan	0.375	0.125	0.125	0.25
2021	nan	nan	0.25	0.5	nan	0.25	nan

I want to rearrange the columns such the the first row is sorted from largest to smallest. So the order of the columns should be Mercedes, Audi/Volvo, the rest.

I tried df.sort_values() so many times, but I always get errors. The most common error is about the usage of by.

Answer 1

You can reorder the columns based on the sorted order of the first row:

out = df[df.iloc[0].sort_values(ascending=False).index]
print(out)

# Output
      Mercedes  Audi  Volvo  Hyundai   Kia  Tesla     VW
2019     0.500  0.25   0.25      NaN   NaN    NaN    NaN
2020     0.375   NaN   0.25    0.125   NaN  0.125  0.125
2021     0.500   NaN    NaN      NaN  0.25    NaN  0.250