CODEWITHSUNDEEP
pythongraphnetworkx
ANNABA Naruto
ANNABA Naruto

Reputation: 9

how to fix the problem of the node is not in graph

i'm creating a program that get the neighbors of nodes in graph from edgelist but the problem is he show me this error

A=nx.all_neighbors(G,1)

File"C:\Users\Toshiba\Anaconda2\lib\sitepackages\networkx\classes\function.py", line 838, in all_neighbors  values = graph.neighbors(node)

File "C:\Users\Toshiba\Anaconda2\lib\site-packages\networkx\classes\graph.py", line 1130, in neighbors

raise NetworkXError("The node %s is not in the graph." % (n,))

NetworkXError: The node 1 is not in the graph.

import networkx as nx
import os


A =os.path.realpath("last_exuction.txt")
fh=open(A, 'rb')
G=nx.read_edgelist(fh)
fh.close()

A=nx.all_neighbors(G,1)

and the content of the file last_exuction.txt 

2 1
3 1
3 2
4 1
4 2
4 3
5 1
6 1
7 1
7 5
7 6
8 1
8 2
8 3
8 4
9 1
9 3
10 3
11 1
11 5
11 6
12 1
13 1
13 4
14 1
14 2
14 3
14 4
17 6
17 7
18 1
18 2
20 1
20 2
22 1
22 2
26 24
26 25
28 3
28 24
28 25
29 3
30 24
30 27
31 2
31 9
32 1
32 25
32 26
32 29
33 3
33 9
33 15
33 16
33 19
33 21
33 23
33 24
33 30
33 31
33 32
34 9
34 10
34 14
34 15
34 16
34 19
34 20
34 21
34 23
34 24
34 27
34 28
34 29
34 30
34 31
34 32
34 33

Upvotes: 1

Views: 7259

Answers (2)

Bisma Dar
Bisma Dar

Reputation: 35

i got the same error ,when i tried to print nodes from the graph created by the code script mentioned below:

   'A =os.path.realpath("last_exuction.txt")
   fh=open(A, 'rb')
   G=nx.read_edgelist(fh)
   fh.close()'

but when I this code snippet:

    from tqdm import tqdm
    import csv
    with open('lastfm_asia_edges.csv', 'r') as f:
      data = csv.reader(f)
      headers = next(data)
      for row in tqdm(data):
          G.add_node(row[0]) #superhero in first column
          G.add_node(row[1]) #superhero in second column
          if G.has_edge(row[0], row[1]):

         # edge already exists, increase weight by one
          G[row[0]][row[1]]['weight'] += 1
          else:
         # add new edge with weight 1
          G.add_edge(row[0], row[1], weight = 1)'

it may resolve this Networkx error problem.

Upvotes: 0

Joel
Joel

Reputation: 23887

Node 1 is not in your graph. I suspect that Node '1' is. That is, the string '1' rather than the integer 1 is in your graph.

This is because when you read the file in, it interprets everything as strings. The documentation shows the optional arguments: read_edgelist(path, comments='#', delimiter=None, create_using=None, nodetype=None, data=True, edgetype=None, encoding='utf-8'). Notice the optional argument nodetype. The documentation says:

nodetype (int, float, str, Python type, optional) – Convert node data from strings to specified type

So do your call as

G=nx.read_edgelist(fh, nodetype = int)

Upvotes: 1

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