Question: I a using NetworkX for a network analysis in python. I determine the weight for every edge and add that edge to the graph in the following way:

```
import matplotlib.pyplot as plt
import networkx as nx
import numpy as np

airports = ['ATL','LAX','ORD']
weights  = [500,200,150] #Note that in my real code I I calculated these weights, they are not provided
G = nx.Graph()
G.add_nodes_from(airports)

weightlst = []
airports_pos = []
checked_airports = []

i = 0
for airport1 in airports:
    for airport2 in airports:
        if airport1 != airport2 and  checked_airports.count([airport1,airport2])==0 and checked_airports.count([airport2,airport1])==0:
            weightedge = weights[i]
            weightlst.append(weightedge)
            weightedge = weightedge*0.0020+0.5
            G.add_edge(airport1, airport2, weight=weightedge)
    checked_airports.append([airport1,airport2])
    i = i + 1

```

For context, the weight of each edge indicates how many flights occur between two airports, and my issue is that it is unclear which 'routes' are 'busiest' because the irrelevant edges are drawn over the relevant ones. I wish to draw the edges with the highest weight last so that it is clear which are the 'busiest flight routes' in the network.

Answer: 
Use:

```
edges=sorted(G.edges(data=True), key=lambda t: t[2].get('weight', 1))

```
Adding to the selected answer since it can feel somewhat complicated... (can't comment due to insufficient reputation and edit request rejected ¯\*(ツ)*/¯)

`G.edges` returns a list of edges added to graph `G` (each edge represented by a ***tuple*** of two elements: the start node and the end node), setting its `data` attribute to `True` includes the weight which was set for each edge in that list as the third element of the ***tuple*** as a dictionary, where the weight's key is the attribute name that has been set for the edge weights (which is by default `'weight'`).

The lambda function evaluates each ***tuple*** `t` and compares them via the third element (which is the dictionary) by fetching the value corresponding to the key `'weight'`, defaulting to 1 if that key is not found.

***It is to be noted that*** if you've chosen an attribute name other than `'weight'` for the edge weight, the above line of code will not work and will not show any errors either, it will just do nothing; for it will default to returning `1` in all cases as it can't find the key and hence effectively sort nothing. An edge can have different attributes of different interpretations, so make sure to choose the key based on which you'd like to sort.