Get two return values from Pandas apply

Question

I'm trying to return two different values from an apply method but I cant figure out how to get the results I need.

With a function as:

def fun(row):
    s = [sum(row[i:i+2]) for i in range (len(row) -1)]
    ps = s.index(max(s))
    return max(s),ps

and df as:

    6:00    6:15    6:30    
0   3       8       9       
1   60      62      116     

I'm trying to return the max value of the row, but i also need to get the index of the first value that produces the max combination.

df["phour"] = t.apply(fun, axis=1)

I can get the output I need, but I don't know how I can get the index in a new column.So far im getting both answer in a tuple

    6:00    6:15    6:30    phour
0   3       8       9       (17, 1)
1   60      62      116     (178, 1)

How can I get the index value in its own column?

Answer 1

You can apply pd.Series

df.drop('Double', 1).join(df.Double.apply(pd.Series, index=['D1', 'D2']))

   A  B  C  D1  D2
0  1  2  3   1   2
1  2  3  2   3   4
2  3  4  4   5   6
3  4  1  1   7   8

---

Equivalently

df.drop('Double', 1).join(
    pd.DataFrame(np.array(df.Double.values.tolist()), columns=['D1', 'D2'])
)

setup
using @GordonBean's df

df = pd.DataFrame({'A':[1,2,3,4], 'B':[2,3,4,1], 'C':[3,2,4,1], 'Double': [(1,2), (3,4), (5,6), (7,8)]})

Answer 2

You can get the index in a separate column like this:

df[['phour','index']] = df.apply(lambda row: pd.Series(list(fun(row))), axis=1)

Or if you modify fun slightly:

def fun(row):
    s = [sum(row[i:i+2]) for i in range (len(row) -1)]
    ps = s.index(max(s))
    return [max(s),ps]

Then the code becomes a little less convoluted:

 df[['phour','index']] = df.apply(lambda row: pd.Series(fun(row)), axis=1)