Liqun Liu - Academia.edu (original) (raw)

Papers by Liqun Liu

Research paper thumbnail of GROUPSET: A Set-Based Technique to Explore Time-Varying Data

HAL (Le Centre pour la Communication Scientifique Directe), Jun 14, 2022

We introduce GroupSet, a technique to facilitate the exploration of temporal charts using a set-b... more We introduce GroupSet, a technique to facilitate the exploration of temporal charts using a set-based approach. GroupSet operates in a twofold way: first it classifies temporal data into categories (sets) for each time point, second it enables to explore such membership to categories (sets) over time. This approach enables to reveal temporal similarities of elements by categories (sets) memberships, usually hidden by overplot. We demonstrate the applicability of the technique to two case studies (traffic data and sport data) and report on usability feedback of an interactive prototype implementing the technique. Our code and datasets are published as an open-source project and we expect further research towards efficient set creation and temporal manipulation, which remain under-explored areas in the domain of set visualization and interaction.

Research paper thumbnail of A Generic Interactive Membership Function for Categorization of Quantities

IEEE Computer Graphics and Applications, 2023

Research paper thumbnail of Research on taxi drivers' passenger hotspot selecting patterns based on GPS data: A case study in Wuhan

2017 4th International Conference on Transportation Information and Safety (ICTIS), 2017

Taxis are the most important components for public transit systems. The model of taxis is more fl... more Taxis are the most important components for public transit systems. The model of taxis is more flexible and convenient for passengers compared to other transit model like buses or railway. However, the dynamic of taxi locations will have influence on transit efficiency. Therefore, the hotspot selecting patterns when unoccupied with regards to different income level drivers were investigated in this study. Two month GPS data of 7200 taxis in Wuhan was used as the data samples. The Wuhan City was firstly Mapped Meshing and divided into 4623 grids. After preprocessing the taxi GPS data and taxi drivers' income level classification (top, ordinary and bottom), the pickup points were filtered and matched with all these grids. Heat and grid probability for passenger demand hotspot were proposed and analyzed in this study. The results showed that the correlation value between top drivers and heat are not always higher than ordinary taxi drivers but the correlation value between grid probability and top taxi drivers are always high at all time slots. The finding of this study reveals that the high income taxis drivers have the high ability for cruising to the closed hotspot having high grid probability compared with middle or low income drivers. It therefore recommended that, if such experience could be represented and learned by other taxi drivers, the efficiency of taxi transit systems will be improved. Furthermore, if the information of real time heat and grid probability of hotspot could be broadcasted to taxi drivers, it will be beneficial for taxi transit systems as well.

Research paper thumbnail of MULTISET: An Interactive Visual Analysis Tool for Multidimensional Quantitative Data

We introduce MULTISET, a novel visualization technique for analyzing the distribution of multi-di... more We introduce MULTISET, a novel visualization technique for analyzing the distribution of multi-dimensional quantitative data, which combines the cumulative distribution function for categorizing quantitative data into categories and a matrix layout for aggregating the elements with the same distributions among generated categories to represent how these elements’ multi-dimensional values distribute. Moreover, the attributes of elements in certain group are represented with the following view of matrix layout. In the future, we will also conduct a user study to evaluate the performance of MULTISET.

Research paper thumbnail of Categorizing Quantities using an Interactive Fuzzy Membership Function

In this paper, we investigate how an interactive version of the membership function from the Fuzz... more In this paper, we investigate how an interactive version of the membership function from the Fuzzy Logic Theory can be used to categorize quantitative data. This function is simple and similar to a line chart and provides an explicit mapping of the categorization process. We first review the requirements for such quantitative values partitioning process and provide the fuzzy logic mathematical foundations related to the membership function. We then report on the implementation of the interactive function for several quantitative datasets case studies (e. g., age, temperature, speed). We expect this interactive function to provide more control over the categorization process, as well as a way to make the categorization more explicit.

Research paper thumbnail of GROUPSET: A Set-Based Technique to Explore Time-Varying Data

HAL (Le Centre pour la Communication Scientifique Directe), Jun 14, 2022

We introduce GroupSet, a technique to facilitate the exploration of temporal charts using a set-b... more We introduce GroupSet, a technique to facilitate the exploration of temporal charts using a set-based approach. GroupSet operates in a twofold way: first it classifies temporal data into categories (sets) for each time point, second it enables to explore such membership to categories (sets) over time. This approach enables to reveal temporal similarities of elements by categories (sets) memberships, usually hidden by overplot. We demonstrate the applicability of the technique to two case studies (traffic data and sport data) and report on usability feedback of an interactive prototype implementing the technique. Our code and datasets are published as an open-source project and we expect further research towards efficient set creation and temporal manipulation, which remain under-explored areas in the domain of set visualization and interaction.

Research paper thumbnail of A Generic Interactive Membership Function for Categorization of Quantities

IEEE Computer Graphics and Applications, 2023

Research paper thumbnail of Research on taxi drivers' passenger hotspot selecting patterns based on GPS data: A case study in Wuhan

2017 4th International Conference on Transportation Information and Safety (ICTIS), 2017

Taxis are the most important components for public transit systems. The model of taxis is more fl... more Taxis are the most important components for public transit systems. The model of taxis is more flexible and convenient for passengers compared to other transit model like buses or railway. However, the dynamic of taxi locations will have influence on transit efficiency. Therefore, the hotspot selecting patterns when unoccupied with regards to different income level drivers were investigated in this study. Two month GPS data of 7200 taxis in Wuhan was used as the data samples. The Wuhan City was firstly Mapped Meshing and divided into 4623 grids. After preprocessing the taxi GPS data and taxi drivers' income level classification (top, ordinary and bottom), the pickup points were filtered and matched with all these grids. Heat and grid probability for passenger demand hotspot were proposed and analyzed in this study. The results showed that the correlation value between top drivers and heat are not always higher than ordinary taxi drivers but the correlation value between grid probability and top taxi drivers are always high at all time slots. The finding of this study reveals that the high income taxis drivers have the high ability for cruising to the closed hotspot having high grid probability compared with middle or low income drivers. It therefore recommended that, if such experience could be represented and learned by other taxi drivers, the efficiency of taxi transit systems will be improved. Furthermore, if the information of real time heat and grid probability of hotspot could be broadcasted to taxi drivers, it will be beneficial for taxi transit systems as well.

Research paper thumbnail of MULTISET: An Interactive Visual Analysis Tool for Multidimensional Quantitative Data

We introduce MULTISET, a novel visualization technique for analyzing the distribution of multi-di... more We introduce MULTISET, a novel visualization technique for analyzing the distribution of multi-dimensional quantitative data, which combines the cumulative distribution function for categorizing quantitative data into categories and a matrix layout for aggregating the elements with the same distributions among generated categories to represent how these elements’ multi-dimensional values distribute. Moreover, the attributes of elements in certain group are represented with the following view of matrix layout. In the future, we will also conduct a user study to evaluate the performance of MULTISET.

Research paper thumbnail of Categorizing Quantities using an Interactive Fuzzy Membership Function

In this paper, we investigate how an interactive version of the membership function from the Fuzz... more In this paper, we investigate how an interactive version of the membership function from the Fuzzy Logic Theory can be used to categorize quantitative data. This function is simple and similar to a line chart and provides an explicit mapping of the categorization process. We first review the requirements for such quantitative values partitioning process and provide the fuzzy logic mathematical foundations related to the membership function. We then report on the implementation of the interactive function for several quantitative datasets case studies (e. g., age, temperature, speed). We expect this interactive function to provide more control over the categorization process, as well as a way to make the categorization more explicit.