pandas 对每一列数据进行标准化的方法

> import numpy as np 
> import pandas as pd 
Backend TkAgg is interactive backend. Turning interactive mode on. 
> np.random.seed(1) 
> df_test = pd.DataFrame(np.random.randn(4,4)* 4 + 3) 
> df_test 
   0   1   2   3 
0 9.497381 0.552974 0.887313 -1.291874 
1 6.461631 -6.206155 9.979247 -0.044828 
2 4.276156 2.002518 8.848432 -5.240563 
3 1.710331 1.463783 7.535078 -1.399565 
> df_test_1 = df_test 
> df_test.apply(lambda x: (x - np.min(x)) / (np.max(x) - np.min(x))) #方法一 
   0   1   2   3 
0 1.000000 0.823413 0.000000 0.759986 
1 0.610154 0.000000 1.000000 1.000000 
2 0.329499 1.000000 0.875624 0.000000 
3 0.000000 0.934370 0.731172 0.739260 
 
> (df_test_1 - df_test_1.min()) / (df_test_1.max() - df_test_1.min())#方法二 
   0   1   2   3 
0 1.000000 0.823413 0.000000 0.759986 
1 0.610154 0.000000 1.000000 1.000000 
2 0.329499 1.000000 0.875624 0.000000 
3 0.000000 0.934370 0.731172 0.739260