[Numpy]np.select

np.select(condition_list, choice_list, default)

 

x = np.arange(10)

>>> condlist = [x<3, x>5]

>>> choicelist = [x, x**2]

>>> np.select(condlist, choicelist)

array([ 0, 1, 2, 0, 0, 0, 36, 49, 64, 81])

 

 

-condition_list에서 여러개  condition을 만족한다면 first encounter condition에 해당하는 choice를 적용함

-default는 어떠한 condition 도 만족하지 않는 경우 output value

 

ex)

condlist = [

(score_df['average'] >= 90),

(score_df['average'] < 90) & (score_df['average'] >= 80),

(score_df['average'] < 80) & (score_df['average'] >= 70)]

choicelist = ['A','B','C']

 

score_df['Grade'] = np.select(condlist, choicelist)