[igraph] Starting with python version

[Simone Caschili]

Hi,

I'm trying to start using Igraph python version. I'm getting some troubles both because i'm a newbye programmer and   Ican't find a really good user guide like those written for Igraph C version.  
Anyway, I have a .txt file in which there is stored my network. For each row I've got something like:

node1 node2 weight

I'm trying to build a graph using Igraph. The code I'm using is this:
 
[code]
from igraph import * 
import string
edges=[]
weights=[]
SP_data=open("test_graph.dat",'r')
SP_data.readline()
while 1:
    line=SP_data.readline() 
    if not line:
        break
    split_line=string.split(line,' ')
    edges.append((split_line[0][0:],split_line[1][0:])) 
     weights.append(float(split_line[2][0:-1]))
 A=int(len(edges))
g=Graph(A,edges,directed=False)
g.vs["weight"]=weights
print edge_attributes()
SP_data.close()
[/code]

but it doesn't work ... I get this message error:

"Traceback (most recent call last): 
  File "getting_net.py", line 17, in ?
    g=Graph(A,edges,directed=False)
TypeError: List elements must be non-negative integer pairs"

If in the wrong line I write the exact number of edge (instead of write the variable A) I get the same error message. 
 
Is there anyone who can help me?

Thank you
Simone C.