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pythonpandasdataframenetworkxcosine-similarity

Create NetworkX graph from similarity matrix


I'm new to the world of graphs and would appreciate some help :-)

I have a dataframe with 10 sentences and I calculated the cosine similarity between each sentence.

Original Dataframe:

    text
0   i like working with text    
1   my favourite colour is blue and i like beans
2   i have a cat and a dog that are both chubby Pets
3   reading is also working with text just in anot...
4   cooking is great and i love making beans with ...
5   my cat likes cheese and my dog likes beans
6   in some way text is a bit boring
7   cooking is stressful when it is too complicated
8   pets can be so cute but they are often a lot o...
9   working with pets would be a dream job

Calculate cosine similarity:

from sklearn.feature_extraction.text import TfidfVectorizer
from sklearn.metrics.pairwise import cosine_similarity

k = test_df['text'].tolist()

# Vectorise the data
vec = TfidfVectorizer()
X = vec.fit_transform(k) 

# Calculate the pairwise cosine similarities 
S = cosine_similarity(X)

# add output to new dataframe 
print(len(S))
T  = S.tolist()
df = pd.DataFrame.from_records(T)

Output for cosine similiarties:

    0   1   2   3   4   5   6   7   8   9
0   1.000000    0.204491    0.000000    0.378416    0.110185    0.000000    0.158842    0.000000    0.000000    0.282177
1   0.204491    1.000000    0.072468    0.055438    0.333815    0.327299    0.064935    0.112483    0.000000    0.000000
2   0.000000    0.072468    1.000000    0.000000    0.064540    0.231068    0.000000    0.000000    0.084140    0.000000
3   0.378416    0.055438    0.000000    1.000000    0.110590    0.000000    0.375107    0.097456    0.000000    0.156774
4   0.110185    0.333815    0.064540    0.110590    1.000000    0.205005    0.057830    0.202825    0.000000    0.071145
5   0.000000    0.327299    0.231068    0.000000    0.205005    1.000000    0.000000    0.000000    0.000000    0.000000
6   0.158842    0.064935    0.000000    0.375107    0.057830    0.000000    1.000000    0.114151    0.000000    0.000000
7   0.000000    0.112483    0.000000    0.097456    0.202825    0.000000    0.114151    1.000000    0.000000    0.000000
8   0.000000    0.000000    0.084140    0.000000    0.000000    0.000000    0.000000    0.000000    1.000000    0.185502
9   0.282177    0.000000    0.000000    0.156774    0.071145    0.000000    0.000000    0.000000    0.185502    1.000000

I now want to create a graph from both dataframes where my nodes are the sentences which are connected through the cosine smiliarty (edges). I have added the nodes as you can see below, but I'm not sure how to add the edges?

### Build graph
G = nx.Graph()

# Add node
G.add_nodes_from(test_df['text'].tolist())


# Add edges 
G.add_edges_from()
 

Solution

  • You could set the indices and column names in df as the text column in your input dataframe (nodes in the network), and build a graph from it as an adjacency matrix using nx.from_pandas_adjacency:

    df_adj = pd.DataFrame(df.to_numpy(), index=test_df['text'], columns=test_df['text'])
    G = nx.from_pandas_adjacency(df_adj)
    

    G.edges(data=True)
    EdgeDataView([('i like working with text    ', 'i like working with text    ', {'weight': 1.0}), 
                  ('i like working with text    ', 'my favourite colour is blue and i like beans', {'weight': 0.19953178577876396}),
                  ('i like working with text    ', 'reading is also working with text just in anot...', {'weight': 0.39853956570404026})
                  ...