If else 语句在自定义 python function 中不起作用

Question

Below is a minimum reproducible example of what I'm trying to achieve with my custom function. The function works if I remove the if statement and second argument. I know the error is derived from the if statement, but I can't seem to figure out what the solution is.

df = pd.DataFrame({"odds":[100, -200, -400], "favorite":[0, 1, 1]})

def odd_bin_group_fn(odds, favorite):
    if (odds <= -200 and favorite == 1):
        return('large_favorite')
    else:
        return('other')

df['odd_bin'] = odd_bin_group_fn(df["odds"], df["favorite"])

Answer 1

Just use anonymous function and apply() method:

df['odd_bin']=df.apply(lambda x:'large_favorite' if (x['odds']<=-200) & (x['favorite']==1) else 'other',1)

OR

You can also use numpy's where() method:

df['odd_bin']=np.where((df['odds']<=-200) & (df['favorite']==1),'large_favorite','other')

Answer 2

To apply function on rows, you can use apply() with axis=1 .

df['odd_bin'] = df.apply(lambda row: odd_bin_group_fn(row["odds"], row["favorite"]), axis=1)

print(df)

   odds  favorite         odd_bin
0   100         0           other
1  -200         1  large_favorite
2  -400         1  large_favorite