Pandas Dataframe apply() method row object vanishes
See the following code. Does it mean I have to go via route `.iterrows`?

``` python
df = pd.DataFrame({'x': range(5)})
df['y'] = df['x'].astype(str)
b = df.apply(lambda row: [row], axis=1)
0    [[nan, nan]]
1    [[nan, nan]]
2    [[nan, nan]]
3    [[nan, nan]]
4    [[nan, nan]]
```
