Get max value from row of a dataframe in python [d

问题:

This question already has answers here:

Find the max of two or more columns with pandas (2 answers)

How to select max and min value in a row for selected columns (1 answer)

Closed 2 years ago.

This is my dataframe df

a     b     c
1.2   2    0.1
2.1   1.1  3.2
0.2   1.9  8.8
3.3   7.8  0.12

I'm trying to get max value from each row of a dataframe, I m expecting output like this

max_value
   2
  3.2
  8.8
  7.8 

This is what I have tried

df[len(df.columns)].argmax()

I'm not getting proper output, any help would be much appreciated. Thanks

回答1:

Use max with axis=1:

df = df.max(axis=1)
print (df)
0    2.0
1    3.2
2    8.8
3    7.8
dtype: float64

And if need new column:

df['max_value'] = df.max(axis=1)
print (df)
     a    b     c  max_value
0  1.2  2.0  0.10        2.0
1  2.1  1.1  3.20        3.2
2  0.2  1.9  8.80        8.8
3  3.3  7.8  0.12        7.8

回答2:

You could use numpy

df.assign(max_value=df.values.max(1))

     a    b     c  max_value
0  1.2  2.0  0.10        2.0
1  2.1  1.1  3.20        3.2
2  0.2  1.9  8.80        8.8
3  3.3  7.8  0.12        7.8