I have a pandas dataframe 'df' with two columns 'A' and 'B', I have a function with two arguments
我有一个pandas数据帧'df',有两列'A'和'B',我有一个带有两个参数的函数
def myfunction(B, A):
# do something here to get the result
return result
and I would like to apply it row-by-row to df using the 'apply' function
我想使用'apply'函数逐行将它应用到df
df['C'] = df['B'].apply(myfunction, args=(df['A'],))
but I get the error
但我得到了错误
ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().
whats happening here, it seems it takes df['A'] as the whole series! not just the row entry from that series as required.
什么发生在这里,似乎需要df ['A']作为整个系列!不仅仅是该系列中的行条目。
1 个解决方案
#1
12
I think you need:
我认为你需要:
import pandas as pd
df = pd.DataFrame({'A':[1,2,3],
'B':[4,5,6]})
print (df)
A B
0 1 4
1 2 5
2 3 6
def myfunction(B, A):
#some staff
result = B + A
# do something here to get the result
return result
df['C'] = df.apply(lambda x: myfunction(x.B, x.A), axis=1)
print (df)
A B C
0 1 4 5
1 2 5 7
2 3 6 9
Or:
def myfunction(x):
result = x.B + x.A
# do something here to get the result
return result
df['C'] = df.apply(myfunction, axis=1)
print (df)
A B C
0 1 4 5
1 2 5 7
2 3 6 9
#1
12
I think you need:
我认为你需要:
import pandas as pd
df = pd.DataFrame({'A':[1,2,3],
'B':[4,5,6]})
print (df)
A B
0 1 4
1 2 5
2 3 6
def myfunction(B, A):
#some staff
result = B + A
# do something here to get the result
return result
df['C'] = df.apply(lambda x: myfunction(x.B, x.A), axis=1)
print (df)
A B C
0 1 4 5
1 2 5 7
2 3 6 9
Or:
def myfunction(x):
result = x.B + x.A
# do something here to get the result
return result
df['C'] = df.apply(myfunction, axis=1)
print (df)
A B C
0 1 4 5
1 2 5 7
2 3 6 9