Python: 'ValueError: can only convert an array of size 1 to a Python scalar' when looping over rows in pd.DataFrame

FYI,

You will get similar error if you are applying .item to a numpy array.

You can solve it with .tolist() in that case.

pd.Series.item requires at least one item in the Series to return a scalar. If:

df[(df['date_rank'] == next_home_fixture) & (df['localteam_id'] == df.at[index,'localteam_id'])]

is a Series with length 0, then the .index.item() will throw a ValueError.