Data Processing

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The data from the server was extracted and saved as four distinct ‘.json’ files, while the GPS records were exported and read as ‘.csv’ files using Jupyter Notebook. The beacon dataset contains all beacon related information as nested list of dictionaries within 2 columns: ‘beacons’ and ‘ibeacon’. To get useful beacon information, we extracted and expanded those columns, and then merged the beacon dataset with GPS location datasets using timestamps. Consequently, we achieved a consolidated dataset with 28 columns containing all information about beacon signals detected and the GPS coordinates.

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The dataset was reduced using the 30-second method. The resulting dataset was then merged with census geometries and manufacturing company details. Reverse Geocoding was applied on this merged dataset to obtain street level address information of each beacon.

The resultant dataset was further reduced to account for duplicate signals from the same device. According to studies, the broadest coverage range of beacon devices is 40 meters, and the average walking speed of normal females between the age of 20 and 39 is 1.37 meters per second. As per calculations based on the above, our data collection team that consists of three female members are found to be out of coverage range of the beacon detected in the last 30 seconds. Thus, it is assumed that the signals with the same set of UUID, major and minor detected within 30 seconds are from the same beacon device, and are removed.

The resulting dataset was then merged with census geometries and manufacturing company details. Time spent on each census tract was calculated and reverse Geocoding was applied on this merged dataset to obtain street level address information of each beacon.

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Sources:

Cronkleton, E. (2019). Average walking speed: Pace, and comparisons by age and sex. Healthline. Retrieved November 24, 2021, from https://www.healthline.com/health/exercise-fitness/average-walking-speed#average-speed-by-age.  

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Ble beacons for indoor positioning : No Bull, Beacon Review. Locatify. (2020). Retrieved November 24, 2021, from https://locatify.com/blog/ble-beacons-no-bull-beacon-review/.