让城市区域表示同时具备空间一致性与任务针对性,提升预测准确率。
ToPT: Task-Oriented Prompt Tuning for Urban Region Representation Learning
- 用图注意力机制注入距离和中心度,建模空间一致的区域关系。
- 通过大模型生成任务语义向量,与区域嵌入动态对齐,提升任务适配性。
- 适用于城市犯罪预测、资源分配等多场景,性能最高提升64.2%。
从异构城市数据中学习有效的区域嵌入是城市计算任务(如犯罪预测、资源分配)的基础。然而,现有两阶段方法生成的任务无关表示,与下游目标脱钩。基于提示的方法虽试图解决此问题,但常缺乏显式空间先验,导致区域间建模空间不一致,且缺少明确的任务语义对齐机制。本文提出ToPT,一个两阶段框架,实现空间一致融合与显式任务对齐。ToPT包含两个模块:空间感知区域嵌入学习(SREL)和面向任务的区域嵌入提示(Prompt4RE)。SREL采用基于Graphormer的融合模块,将距离与区域中心度作为可学习注意力偏置注入,捕捉连贯可解释的区域间交互。Prompt4RE执行任务导向提示:冻结的多模态大语言模型(MLLM)处理任务特定模板生成语义向量,通过多头交叉注意力与区域嵌入对齐,实现稳定任务条件化。在多个任务和城市的实验表明,该方法达到当前最优性能,最高提升达64.2%,验证了空间先验与提示-区域对齐的必要性与互补性。代码已开源:https://github.com/townSeven/Prompt4RE.git。
原文摘要 · Abstract (English)
Learning effective region embeddings from heterogeneous urban data underpins key urban computing tasks (e.g., crime prediction, resource allocation). However, prevailing two-stage methods yield task-agnostic representations, decoupling them from downstream objectives. Recent prompt-based approaches attempt to fix this but introduce two challenges: they often lack explicit spatial priors, causing spatially incoherent inter-region modeling, and they lack robust mechanisms for explicit task-semantic alignment. We propose ToPT, a two-stage framework that delivers spatially consistent fusion and explicit task alignment. ToPT consists of two modules: spatial-aware region embedding learning (SREL) and task-aware prompting for region embeddings (Prompt4RE). SREL employs a Graphormer-based fusion module that injects spatial priors-distance and regional centrality-as learnable attention biases to capture coherent, interpretable inter-region interactions. Prompt4RE performs task-oriented prompting: a frozen multimodal large language model (MLLM) processes task-specific templates to obtain semantic vectors, which are aligned with region embeddings via multi-head cross-attention for stable task conditioning. Experiments across multiple tasks and cities show state-of-the-art performance, with improvements of up to 64.2\%, validating the necessity and complementarity of spatial priors and prompt-region alignment. The code is available at https://github.com/townSeven/Prompt4RE.git.
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