Abstract: Focusing on the fact that the order of locations and time play a pivotal role in understanding user mobility patterns for spatio-temporal trajectories, a novel deep representation model for trajectories was proposed. The model considered the characteristics of spatio-temporal trajectories: 1) different orders of locations indicate different user mobility patterns; 2) trajectories tend to be cyclical and change over time. First, two time-ordered locations were combined in location sequence; second, the sequence and its corresponding time bin were combined in the temporal location sequence, which was the basic unit of describing the features of a trajectory; finally, the deep representation model was utilized to train the feature vector for each sequence. To verify the effectiveness of the deep representation model, experiments were designed to apply the temporal location sequence vectors to user mobility patterns mining, and empirical studies were performed on a real check-in dataset of Gowalla. The experimental results confirm that the proposed method is able to discover explicit movement patterns (e.g., working, shopping) and Word2Vec is difficult to discover the valuable patterns.

Key words: spatio-temporal trajectory mining, user mobility pattern, deep representation model, temporal location sequence vector, Huffman coding

摘要： 针对时空轨迹中位置顺序和时间对于理解用户移动模式的重要性,提出了一种新的用户轨迹深度表示模型。该模型考虑到时空轨迹的特点:1)不同的位置顺序表示不同的移动模式;2)轨迹有周期性并且在不同的时间段有变化。首先,将两个连续的位置点组合成位置序列;然后,将位置序列和对应的时间块组合成时间位置序列,作为描述轨迹特征的基本单位;最后,利用深度表示模型为每个序列训练特征向量。为了验证深度表示模型的有效性,设计实验将时间位置序列向量应用到用户移动模式发现中,并利用Gowalla签到数据集进行了实验评测。实验结果显示提出的模型能够发现"上班""购物"等明确的模式,而Word2Vec很难发现有意义的移动模式。

关键词: 时空轨迹挖掘, 用户移动模式, 深度表示模型, 时间位置序列向量, 哈夫曼编码