Finding ultimate parent

Question

I am trying to find the ultimate parent with Dir pandas. But the task has one specialty where the graph doesn't really fit, or I simply don't know how to use it correctly. Input:

Child	Parent	Class
1001	8888	A
1001	1002	D
1001	1002	C
1001	1003	C
1003	6666	G
1002	9999	H

Output:

Child	Ultimate_Parent	Class	Connection
1001	8888	A	Direct
1001	9999	D	Indirect
1001	9999	C	Indirect
1001	6666	C	Indirect
1003	6666	G	Direct
1002	9999	H	Direct

I do:

import pandas as pd 
import networx as nx 
df = pd.DataFrame({'Child': ['1001', '1001', '1001', '1001', '1003', '1004'], 'Parent': ['8888', '1002', '1002', '1003', '6666', '9999'],'Class': ['A','D','C','C','G','H']})
    def get_hierarchy (df):
        DiG=nx.from_pandas_adgelist (df,'child','parent',create_using=nx.DiGraph())
        return pd.DataFrame.from_records([(n1,n2) for n1 in DiG.nodes() for n2 in nx.ancestors(DiG, n1)], columns=['child','Ultimate_parent'])
    df=df.toPandas()
    df=get_hierarchy(df)
    return df

And I can't get how to use Class attribute here, to show twice 1001 with D and C classes.

Answer 1

Use G.predecessors to detect if the current Parent is a root of the tree or not. If yes, the connection is Direct else the connection is Indirect.

G = nx.from_pandas_edgelist(df, source='Parent', target='Child',
                            create_using=nx.DiGraph)

roots = [node for node, degree in G.in_degree() if degree == 0]

ultimate_parent = [node if node in roots else list(G.predecessors(node))[0] 
                       for node in df['Parent']]

df['Ultimate_Parent'] = ultimate_parent
df['Connection'] = np.where(df['Parent'] == df['Ultimate_Parent'],
                            'Direct', 'Indirect')

Output:

>>> df
   Child  Parent Class  Ultimate_Parent Connection
0   1001    8888     A             8888     Direct
1   1001    1002     D             9999   Indirect
2   1001    1002     C             9999   Indirect
3   1001    1003     C             6666   Indirect
4   1003    6666     G             6666     Direct
5   1002    9999     H             9999     Direct