Movement & time
GPS tracks and trajectories: cleaning them, segmenting them, and measuring what moved where.
A trajectory is points with timestamps, and almost every question about it is really a question about the intervals between them. Speed, stop detection, segmentation and map matching are all computed from consecutive pairs, which means one bad fix contaminates two legs rather than one.
GPS error is not noise around a true position: it is a mixture of small jitter, multipath in cities, and occasional fixes that land kilometres away. The track still looks plausible drawn on a map. What gives it away is the implied speed, which is why filtering by plausible velocity comes before anything else, and why a stop is defined by a radius and a duration rather than by a single point.
Below: the concepts cover what a trajectory is and what sampling rate costs you, the how-to guides clean, segment and summarise, and the fixes are the distances and speeds that come back impossible.
🧭 Start with the concepts
The ideas the how-to guides below assume you already have.
⚙️ Then do the task
Step-by-step walkthroughs with code you can copy and adapt.
- How to Load GPS Tracks into Python as Trajectories
- How to Clean a GPS Track: Outliers, Duplicates and Jumps
- How to Calculate Speed, Distance and Direction Along a Track
- How to Split a Track into Trips and Stops in Python
- How to Resample and Interpolate a Track to a Fixed Interval
- How to Map-Match a GPS Track to a Street Network
Show every how-to guide in this topic
- How to Aggregate Movement into Flows Between Zones
- How to Animate Movement Over Time in Python
- How to Resample a Gridded Time Series to Monthly or Annual Values
- How to test whether GPS traces reveal where people live
- How to clean AIS vessel tracks in Python
- How to Map a Hurricane Track from IBTrACS in Python
- How to Analyse Origin–Destination Flows by Hour of Day in Python
- How to Analyse Cyclist Casualties from STATS19 in Python
- How to Separate Commuting from Leisure in Bike-Share Trips
- How to Follow an Aircraft Through Its Day and Measure Delay Propagation
- How to Build Hour-of-Day Traffic Profiles from Manual Counts
- How to Measure Cycling from Road Traffic Counts
- How to Calculate Traffic Speeds by Hour from Taxi Trips
- How to Compare Uber and Lyft with Yellow Taxis Using TLC High-Volume Data
🔧 When it breaks
The errors this topic produces, with the cause explained rather than just the command.
Learning paths through this topic
A curated route rather than a list — the guides in the order that builds on itself.
Related topics
Subjects that keep coming up alongside this one, most overlap first.