Enriching Large-Scale Trips With Fine-Grained Travel Purposes: A Semi-Supervised Deep Graph Embedding Framework

Abstract

Knowing why people travel is meaningful for human mobility understanding and smart services development. Unfortunately, in real-world scenarios, trip purpose cannot be automatically collected on a large scale, thus calling for effective prediction models. Nevertheless, since passengers’ trip purposes in the city are diverse and complicated, the prediction is very difficult especially at a fine-grained level. Worse still, the informative data sources and real purpose-labels about trips are commonly limited for model learning. To resolve the dilemma, we propose a semi-supervised deep embedding framework for predicting fine-grained trip purposes on a large scale. Specifically, we first derive augmented trip contexts from the vehicle’s GPS trajectory and public POI check-in data, then convert POI contexts into the graph structure. We further establish a Dual-Attention Graph Embedding Network with Autoencoder architecture ( DAGE-A) to accomplish prediction and reconstruction simultaneously, in which category-aware graph attention networks are devised to model the POI semantics at trip’s origin/destination and extract complementary knowledge from unlabeled trips; and soft-attention is employed to aggregate different trip semantics appropriately for the final prediction. We conduct extensive experiments in Beijing and Shanghai, and results show our framework outperforms state-of-the-arts and could reduce labelling efforts by up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$20\%$</tex-math> </inline-formula> . We also find that our model is generalized at different times and locations, and the performance varies for different trip purposes.