Grouping all connected nodes of a dataset

Question

This is not a duplicate of:

Fastest way to perform complex search on pandas dataframe

Note: pandas ver 0.23.4

Assumptions: data can be laid out in any o

Answer 1

You could define a graph using the values from both columns as edges, and look for the connected_components. Here's a way using NetworkX:

import networkx as nx

G=nx.Graph()
G.add_edges_from(df.values.tolist())
cc = list(nx.connected_components(G))
# [{'A', 'B', 'C', 'D'}, {'L', 'M', 'N', 'O'}]

Now say for instance you want to filter by D, you could then do:

component = next(i for i in cc if 'B' in i)
# {'A', 'B', 'C', 'D'}

And index the dataframe where the values from both columns are in component:

df[df.isin(component).all(1)]

   Col1 Col2
0    A    B
1    B    C
2    D    C

---

The above can be extended to all items in the list, by generating a list of dataframes. Then we simply have to index using the position in which a given item is present in L:

L = ['A', 'B', 'C', 'D', 'L', 'M', 'N', 'O']

dfs = [df[df.isin(i).all(1)] for j in L for i in cc if j in i]
print(dfs[L.index('D')])

   Col1 Col2
0    A    B
1    B    C
2    D    C

print(dfs[L.index('L')])

   Col1 Col2
3    L    M
4    M    N
5    N    O