## 4 Research Process
### Data Extraction by Classification
#### 4.2.1 Citizen Sensing by User Check-In
According to the definition of a linear equation, if the single variable \(y\) has a linear relationship with variable \(x\), then the function of \(y\) and \(x\) is:  
\[y=ax+b \tag{1}\]  
The hypothesis of this experiment is that if an index of a city environment, for example, \(F(c)\), has a linear relationship with citizen feelings, then the function of \(F(c)\) is:  
\[y=F(c),\ x=c_{n}F(c)=ac_{n}+b,\ a\ and\ b\ are\ constants \tag{2}\] \begin{table}
\begin{tabular}{c c c c} \hline \hline
**No.** & **Please Provide the Traffic Detail of Your Mark** & **Options** \\ \hline Q1 & What the transportation are you going to choose? & Walking/Bicycle/Electric scooter/Sooter/Public transport/Vehicle/Others \\ \hline Q2 & Do you see any of the facilities as below at your location? (Multiple selection) & Sidewalks/Pedestrians signs/Barrier-free facilities/Bicycle lanes /Bicke rental station/Scooters parking spaces/Electric scooters swap stations/Gas stations/Bus stations/MRT stations/Escalators/Car parking spaces/Others_ (Self-input) \\ \hline Q3 & How many lines is the street or road in? (Single selection) & Six-lane road/Four-lane road/Two-lane road/Single-lane road/One-way road/Unplanned road/Hard to determine \\ \hline Q4 & How convenient is it to move in the direction of your choice? (Single selection) & Quite convenient/Convenient/Acceptable/Inconvenient/Quite inconvenient \\ \hline Q5 & How do the buildings look like at your position? (Single selection) & Many tall buildings/Flat buildings/Less buildings/Others_ (Input description) \\ \hline Q6 & Is there any clearly landmark? & No/Yes (Input description) \\ \hline Q7 & How is your evaluation to this environment? (Single selection) & Excellent/Good/Average/Fair/Poor \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Questionnaire used in extraction system to determine citizen feelings. This is the questionnaire implemented in the check-in system on the website. Each selection sends a number to the database. For example, in Q7, when the user feels better in the environment, the number is bigger. All of the numbers are integers. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**No.** & **Description** & **Algebra** & **Function** & **Information Classification** \\ \hline Q1 & Transportation Kind & \(c_{0}\) & \(F(c)\) & Personal Feelings/Selection \\ \hline Q2 & Traffic Facility & \(a_{2}\) & & Traffic Accessibility \\ \hline Q3 & Lines of Roads & \(a_{3}\) & & Traffic Accessibility \\ \hline Q4 & Convenience & \(a_{4}\) & & Traffic Accessibility \\ \hline Q5 & Buildings & \(e_{5}\) & \(U(\text{e})\) & Urbanization \\ \hline Q6 & Landmarks & \(e_{6}\) & & Urbanization \\ \hline Q7 & Environment & \(c_{7}\) & \(F(c)\) & Personal Feelings/Selection \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Functional definitions of questionnaire answers. Briefly, the questionnaire answers are converted into algebra and functions. According to the check-in data acquired from the extraction system used to organize citizen feelings, the algebra and functions were set as seen below (Table 3). Besides the constitution of the citizen feeling functions, the relationship of the environment indexes is also verified by a linear equation. There were seven questions included in the questionnaire, and Questions 1 and 7 concerned citizens' personal feelings about how and why they were in their present location. These questions were classified as personal feelings and selections with a functional codename of \(F(c)\). Questions 2, 3, and 4 were about traffic construction in the location and had a functional codename of \(T(a)\). Questions 5 and 6 were about the urban buildings in the location and had a functional codename of \(U(\mathbf{e})\). Although the traffic construction and buildings are objective facts of the urban environment, we asked the users to confirm if construction was conspicuous enough for citizens to \"sense\" it in the environment.