Custom output of edgelist in networkx

Question

I am trying to implement tarjan's algorithm for practice. I decided to generate a random graph to give as input to the algorithm, adding one edge at a time. I generated the random graph and saved it in a file, as shown below ``` from networkx import * import sys import matplotlib.pyplot as plt n = 10 # 10 nodes m = 20 # 20 edges G = gnm_random_graph(n, m) # print the adjacency list to a file try: nx.write_edgelist(G, "test.edgelist", delimiter=',') except TypeError: print "Error in writing output to random_graph.txt" fh = open("test.edgelist", 'rb') G = nx.read_adjlist(fh) fh.close() ``` The output that I got in the test.edgelist file is something like this. ``` 0,4,{} 0,5,{} 0,6,{} 1,8,{} 1,3,{} 1,4,{} 1,7,{} 2,8,{} 2,3,{} 2,5,{} 3,8,{} 3,7,{} 4,8,{} 4,9,{} 5,8,{} 5,9,{} 5,7,{} 6,8,{} 6,7,{} 7,9,{} ``` How ever, in the tarjan's algorithm that I've implemented, the input is in the format ``` add_edge(1,2) add_edge(2,3) .... ``` I wish to use the randomly generated graph in a loop to g…

Accepted Answer

You have to drop all edges data with set `data` parameter to `False`:

```
nx.write_edgelist(G, "test.edgelist", delimiter=',', data = False)
```

Output:

```
0,3
0,4
0,1
0,8
0,6
0,7
```

However if you want to save edges in your own format use a cycle like here:

```
from networkx import gnm_random_graph

n = 10  # 10 nodes
m = 20  # 20 edges

G = gnm_random_graph(n, m)

# iterate over all edges
with open('./test.edgelist', 'w') as f:
    for edge in G.edges():
        f.write("add_edge{0}
".format(edge))
```

Output:

```
add_edge(0, 7)
add_edge(0, 4)
add_edge(0, 8)
add_edge(0, 3)
add_edge(0, 2)
add_edge(1, 5)
add_edge(1, 6)
add_edge(1, 7)
add_edge(2, 5)
add_edge(2, 4)
add_edge(2, 9)
add_edge(2, 8)
add_edge(2, 3)
add_edge(3, 9)
add_edge(3, 5)
add_edge(4, 9)
add_edge(4, 7)
add_edge(5, 9)
add_edge(6, 9)
add_edge(7, 9)
```

Custom output of edgelist in networkx

Solution

Problem