Visual Analysis Of Public Utility Service Problems In A Metropolis Based On Hotline Data

City utility services are guaranteed through normal operations of public infrastructures provided by multiply city agencies. However, ensuring the orderliness of a city at all times can be challenging, because the various issues related to utility service arise due to the increasing rate of city construction, vandalism and so on. Citizens are the main service subjects and they report the issues about utility service based on evidences they witness, so issues reported by citizens can provide unprecedented insights into the various aspects of such utility services for administrators.As increasing volumes of utility service issues are captured, the analysis of these issues can provide evidence-based decision making for administrators and then improve living quality. However, analyzing these issues faces many challenges. These issues are complex, because of the involvement of spatial and temporal components, in addition to having multi-dimensional and multivariate natures. Consequently, exploring utility service problems and creating visual representations are difficult. To analyze these issues effectively, this paper proposes a visual analytics process based on the main tasks of utility service management. The main tasks are analyzing the issues and determining all the events that are caused by utility services promptly. For the analysis of issues, firstly this paper visualizes the distribution of issues by utilizing heatmap and dotmap on the basis of their geographical coordinates. Second, it provides a time-filtered linechart to assist users in identifying temporal patterns or anomalies. Third, it provides a barchart that presents changes in quantity of resolved and unresolved issues, and combines dotmap and heatmap to show solution situation in two-dimensional geographical space. For the analysis of events, this paper proposes an aggregation method that transforms numerous issues into legible events by aggregating correlative issues to an event. The correlation between issues in this aggregation method considers four factors comprehensively including time span, absolute space distance, semantic space similarity and semantic content of issue. At the same time, it provides visualizations of events in order to identify emergencies in time for users including methods based on rectangle, minimum spanning tree and root of event. In a word, the approach, a set of tools and interaction techniques provided by this paper can help users explore issues and emergencies from different perspectives and hierarchies, and then enables administrators to make more informed decisions to solve utility service problems.