Quiz on spatial networks

Check how much you remember from this section by answering the questions below.

In a street network, what do nodes and edges usually represent?

✓Nodes represent intersections, and edges represent street segments connecting them.

✗Nodes represent streets, and edges represent the buildings along them.

✗Nodes represent travel costs, and edges represent geographic areas.

✗Nodes represent destinations, and edges represent travel schedules.

Why might distance along a street network differ from straight-line distance?

✗Street-network distance is always shorter because it follows streets.

✓The route is constrained by the network, so it may not follow the direct path between two places.

✗Straight-line distance accounts for one-way streets, but network distance does not.

✗They are always equal when the network is made from OpenStreetMap.

What does network.nearest_pois() return?

✗The nearest network node to each point of interest.

✗The number of points of interest within the search area.

✓Distances from network nodes to the nearest point(s) of interest, optionally including their IDs.

✗A polygon showing the area around each point of interest.

What does an isochrone represent?

✗The shortest route connecting every pair of destinations.

✓The area reachable from one or more origins within a specified time or distance.

✗The straight-line distance from an origin to its nearest destination.

✗The number of network nodes in a geographic area.

What is the effect of using a linear decay when aggregating values across a network?

✗It gives more influence to values farther away.

✗It removes all values outside the network.

✓It gives less influence to values as network distance increases.

✗It converts distances into travel times using transit schedules.

Why might values be assigned to the nearest existing network node?

✗To ensure every point is exactly on a street intersection.

✓Network analyses use network nodes, so assigning values to nearby nodes links the data to the network.

✗To convert all values into distances.

✗To remove nodes that are not connected to a street.

What information does GTFS provide for modelling public transport?

✗Street geometries and road speed limits only.

✗Population counts at transit stops.

✓Transit routes, stops, schedules, transfers, and related service information.

✗The shortest walking route between any two places.

What does a travel-time matrix contain?

✓Travel times between origin and destination pairs.

✗The coordinates of every intersection in the network.

✗The number of transit routes serving each origin.

✗The polygon boundaries of all reachable areas.

How can travel times be converted into interaction weights?

✗Assign the same weight to every pair of places, regardless of travel time.

✗Use the straight-line distance between place names.

✓Apply a kernel so that shorter travel times receive higher weights and longer times receive lower weights.

✗Replace travel times with the number of transit stops in the dataset.