<｜begin▁of▁sentence｜>### Instruction:
As a construction manager overseeing a large infrastructure project, you're tasked with optimizing the efficiency of material transportation within the construction site. The site comprises different zones interconnected by roads of varying conditions. Each road segment has a weight representing the time it takes for a vehicle to travel from one zone to another. For instance, it takes 1 unit of time to travel from Zone A to Zone B, 2 units from Zone B to Zone C, and so on.

To ensure smooth operations, you need to determine the optimal routing strategy for outgoing transportation from each zone. In this case, you're interested in finding the minimum time it takes for materials to reach the farthest zone reachable from each starting zone, considering only outgoing routes.

In practical terms, this translates to utilizing the `radius` function provided by the network analysis tool you're employing, such as NetworkX or igraph, to calculate the radius of the transportation network. This radius represents the maximum time it takes for materials to reach the farthest zone from any given starting zone, factoring in only the outgoing routes. By understanding this metric, you can efficiently plan material logistics within the construction site, ensuring timely delivery of resources to each area.
### Response:
import igraph as ig

# Create a directed graph with weights
g = ig.Graph(directed=True)
g.add_vertices(5)
g.add_edges([(0, 1), (1, 2), (2, 3), (3, 4)])
g.es['weight'] = [1, 2, 1, 3]

# Calculate the radius of the graph with OUT mode
radius = g.radius(mode='OUT', weights='weight')

print('The radius of the graph is:', radius)
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