python大 pandas 数据帧如果没有迭代思想数据帧 [英] python pandas data frame if else without iterating thought data frame
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问题描述
我想添加一个列到df。这个新df的值将取决于其他列的值。例如
I want to add a column to a df. The values of this new df will be dependent upon the values of the other columns. eg
dc = {'A':[0,9,4,5],'B':[6,0,10,12],'C':[1,3,15,18]}
df = pd.DataFrame(dc)
A B C
0 0 6 1
1 9 0 3
2 4 10 15
3 5 12 18
现在我要添加另一个列D,其值将取决于A,B,C的值。
所以例如,如果是迭代通过df我将做:
Now I want to add another column D whose values will depend on values of A,B,C. So for example if was iterating through the df I would just do:
for row in df.iterrows():
if(row['A'] != 0 and row[B] !=0):
row['D'] = (float(row['A'])/float(row['B']))*row['C']
elif(row['C'] ==0 and row['A'] != 0 and row[B] ==0):
row['D'] == 250.0
else:
row['D'] == 20.0
有没有for循环或使用where()或apply()函数的方法。
Is there a way to do this without the for loop or using where () or apply () functions.
谢谢
推荐答案
code>应该适合你:
apply
should work well for you:
In [20]: def func(row):
if (row == 0).all():
return 250.0
elif (row[['A', 'B']] != 0).all():
return (float(row['A']) / row['B'] ) * row['C']
else:
return 20
....:
In [21]: df['D'] = df.apply(func, axis=1)
In [22]: df
Out[22]:
A B C D
0 0 6 1 20.0
1 9 0 3 20.0
2 4 10 15 6.0
3 5 12 18 7.5
[4 rows x 4 columns]
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