Length Of Values Does Not Match Length Of Index During A For Loop

I have a dataset (df) like this Name1 Name2 Score John NaN NaN Patty NaN NaN where Name2 and Score are initialized to NaN. Some data, like the following name2_list=[[Chris

Solution 1:

I think it is not a good idea to use pandas for this kind of problem. If you are fine with plain python for intermediate steps, you could do this:

import pandas as pd


defget_links(source_name):
    """Dummy function with data from OP.
    
    Note that it processes one name at a time instead of batch like in OP.
    """
    dummy_output = {
        'John': (
            ['Chris', 'Luke', 'Martin'],
            [1, 2, 4]
        ),
        'Patty': (
            ['Martin'],
            [9]
        ),
        'Chris': (
            ['Patty'],
            [9]
        ),
        'Luke': (
            ['Martin'],
            [1]
        ),
        'Martin': (
            ['Laura'],
            [3]
        ),
        'Laura': (
            ['John'],
            [3]
        )
    }
    target_names, scores = dummy_output.get(source_name, ([], []))

    return [
        {'name1': source_name, 'name2': target_name, 'score': score}
        for target_name, score inzip(target_names, scores)
    ]


todo = ['John', 'Patty']

seen = set(todo)
data = []

while todo:
    source_name = todo.pop(0)  # If you don't care about order can .pop() to get last element (more efficient)# get new data
    new_data = get_links(source_name)
    data += new_data

    # add new names to queue if we haven't seen them before
    new_names = set([row['name2'] for row in new_data]).difference(seen)
    seen.update(new_names)
    todo += list(new_names)

pd.DataFrame(data)

Output:

    name1   name2  score
0    John   Chris      1
1    John    Luke      2
2    John  Martin      4
3   Patty  Martin      9
4   Chris   Patty      9
5    Luke  Martin      1
6  Martin   Laura      3
7   Laura    John      3