Introducing the Facility List Coder: A New Dataset/Method to Evaluate Community Food Environments

Abstract

Community food environments have been shown to be important determinants to explain dietary patterns. This data descriptor describes a typical dataset obtained after applying the Facility List Coder (FLC), a new tool to asses community food environments that was validated and presented. The FLC was developed in Python 3.7 combining GIS analysis with standard data techniques. It offers a low-cost, scalable, efficient, and user-friendly way to indirectly identify community nutritional environments in any context. The FLC uses the most open access information to identify the facilities (e.g., convenience food store, bar, bakery, etc.) present around a location of interest (e.g., school, hospital, or university). As a result, researchers will have a comprehensive list of facilities around any location of interest allowing the assessment of key research questions on the influence of the community food environment on different health outcomes (e.g., obesity, physical inactivity, or diet quality). The FLC can be used either as a main source of information or to complement traditional methods such as store census and official commercial lists, among others.

Dataset:https://github.com/jcmunozmora/facilitylistcoder.git

Dataset License: Attribution-Share Alike 4.0 International (CC BY-SA 4.0)

1. Summary

In spite of much qualitative evidence exhibiting the influence of community food environments on food behaviors and health outcomes such as obesity, many quantitative studies have found unexpected or inconsistent results that could indicate that the exposition to a specific food environment might exert influence on eating patterns [1,2,3,4]. Many scholars agree that one of the main explanations for the absence of compelling direct evidence is largely due to one factor: the insufficient validity and reliability of food environment measurements [5]. In fact, in a compilation of literature and a recent systematic review, McKinnon et al. [5] and Lytle et al. [6] showed that only 25% of those studies included in the analysis had any metric evidence that validated their quantitative approach for food environments. Therefore, their results were obtained from poor quality data sources leading to uncertainty, bias, and very low statistical power.

Among the different options to improve the quality and standardization of measuring food environments, the Geographical Information System (GIS) technologies-based solutions stand up. These procedures use the actual positions of the food facilities (i.e., stores, supermarkets, etc.) to calculate different parameters such as facility density or proximity to the nearest facility [7]. Based on these measures, researchers are able to estimate the level and intensity of exposure of a particular subject to a given food environment. Thereby, GIS-based alternatives solve the difficulties of traditional methods, allowing new and important opportunities to finally discern quantitatively the probable relationship between food environments and health outcomes [7].

This data descriptor presents a typical dataset obtained after applying the Facility List Coder (FLC), a tool that was validated and presented in a previous paper [8]. The FLC is an open source Python code that combines GIS analysis with standard data analysis techniques. The FLC extracts geographical information and facility characteristics from two GIS search engines available online: Google Maps and Open Street Maps. These datasets are built using the concept of nodes (or places), which include any geographical objects, such as stores, restaurants, parks, gyms, bridges, and streetlights, among others. Besides the geographical location, each place provides additional information like their description, offers, and characteristics, among others.

2. Data Description

We present a typical dataset obtained after applying the FLC in a given geographical location. In particular, we provided information from Mataró (Spain), a city located near Barcelona (25 km) in Catalonia, Spain, which was used by Arcila et al. [8] as the case study to validate the FLC. Besides other GIS-based solutions [7,9], the FLC collects geographical information and facility characteristics from two main GIS search engines that are available online (Google Maps and Open Street Maps) conducting a spatial query around a predefined zone around a centroid (e.g., schools or homes), then information is classified into four international standardized categories [10]: (i) fast-food restaurants, (ii) bars/restaurants/bakery, (iii) supermarkets, and (iv) specialty stores and others (this dataset is available in the supplementary material). Thus, the final dataset will provide a full description of the food environment around the geographical region of analysis.

2.1. Format

As the main output, the FLC yields a comma-separated file (.csv).

2.2. Data Structure

Table 1. Typical data structure from Facility List Coder output

Variable Name	Type	Description
category	Factor	Facility classification using the predefined classification
dist_cycling	Numeric/Float	Cycling distance from the facility to the interest point
dist_km	Numeric/Float	Road distance from the facility to the interest point
dist_walking	Numeric/Float	Walking time from the facility to the point
geo_id	String	ID from the spatial search engine (google/osm)
geo_web	String	Webpage available from the geo-engine
place_address	String	Facility address
place_lat	Numeric/Float	Facility location—latitude
place_lng	Numeric/Float	Facility location—longitude
place_name	String	Facility name
place_phone_number	String	Facility phone number
place_web	String	Facility webpage (if available)
li_id	Numeric/Float	Location of interest—ID
li_lat	Numeric/Float	Location of interest—latitude
li_lng	Numeric/Float	Location of interest—longitude
li_name	String	Location of interest—name

describes the structure of the output, where each row (unit of analysis) is at a facility located at the predefined buffer zone.

3. Methods

The FLC was developed in Python 3.7 combining GIS analysis with standard data techniques. Besides other GIS-based solutions [7,9], the FLC collects geographical information and facility characteristics from two main GIS search engines that are available online (Google Maps and Open Street Maps) performing a spatial query around a predefined zone around a centroid (e.g., school, hospital, or university), then information is classified based on the metadata available for each location based on a comprehensive, multilanguage list of key words that allows for the categorization of each facility. These datasets are built utilizing the concept of nodes (or places), which include any geographical objects, such as bridges, streetlights, stores, schools, and parks, among others.

The FLC performs a spatial query, retrieving all types of facilities present in a predefined zone (e.g., Euclidean buffer around an interest point or any customizable geographic polygons like street segments). In the case of Google Maps, we used the API that offers a low-cost and efficient spatial query. For Open Street Maps (OSM), we implemented a spatial query taking all nodes that could be classified as facilities. In order to avoid duplicates, the FLC performed different techniques based on location as well as all available metadata.

Once the complete list of facilities was obtained, each facility (e.g., bar, supermarket, convenience food store, bakery, etc.) was automatically filtered and classified using the metadata available in each dataset according to a predefined multilingual (Catalan, Spanish, and English) keyword set. This keyword set was first established using a comprehensive list of types of outlets developed by the Government of Catalonia (Spain) as the reference document [11]. Founded on international classification and specific European outlets, this document provides a classification of 10 different outlet types easily generalizable for any European context [10]. Based on these initial disaggregated subcategories, we built a more aggregated and internationally accepted classification [10], which classifies each facility into four types: (i) fast-food restaurants, (ii) bars/restaurants, (iii) supermarkets, and (iv) convenience stores and others.

Table 2. Classification categories and subcategories.

International Category	Subcategory	Other Information
Bars/Restaurants/Bakery	Bakery	Pastry shop
	Bar, Restaurant	Kiosk
Fast-Food Restaurants	Fast-Food Restaurant	Churreria, frankfurt
	Ice Cream Store	Orcheteria
Supermarkets	Supermarket	Local market, grocery store, frozen store, mini markets
Specialty Stores and Others	Fish Shop
	Fruit, Vegetable Store
	Eggs Store
	Dairy Products	Cheese shop
	Oil Shop
	Butchery	Butcher shop

presents the categories structure applied in the FLC. The four standardized categories provide an accurate classification of facilities in any context compared with the audited data [8]. In contrast, as the automatic classification for subcategories needs more information from each facility, its accuracy might vary among different contexts [8]. Currently, we are working in a new version of the FLC using matching learning techniques to increase the accuracy of the classification for subcategory level in any context.

Buffer-related parameters and facility categories can be modified to satisfy the specific needs of researchers related to geographical location, multilingual search options, or research questions. Even though other researchers have used similar categories [10], the use of our predefined multilingual key word list offers a contribution for researching community food environments outside the US context, as it allows standardizing the local food traditions into an international classification. For instance, in the European context, a specialized nuts store would not have had any classification following the US standards, yet the FLC offers the possibility to adapt these particularities into a traditional classification. That is, the key word list is easily modified and new terms incorporated or deleted depending on the needs of the researchers or the context. Finally, taking advantage of the different measures available for GIS, the FLC provides: (i) the geographical distance taking into account the road network and traffic based on Google API, in kilometers, (ii) the average time of the walking distance, in minutes, and (iii) the average time of the cycling distance taking into account traffic, in minutes. As its main output, the FLC offers a detailed dataset for all the classified facilities located around each point of interest.

Instructions to Use the FLC in Any Specific Context

The main use of the FLC is the evaluation of the community food environment around a specific interest point (e.g., school or university, among others). Thus, users must provide the geo-location of the point or location of interest (LI), and the size of the zone or buffer around the LI in which the food environment will be evaluated. In the literature, the threshold is often defined as around 1 to 1.6 km [12]. For instance, in a performed study of schooling food environment made by the authors (not published), the FLC listed the facilities present around 1 km from each school. Based on this information, the FLC retrieves the full list of facilities located within the defined zone around the LI. Using the predefined key words list, the FLC will generate a dataset where facilities are classified into four types: (i) fast-food restaurants, (ii) bars/restaurants, (iii) supermarkets, and (iv) convenience stores and others. Despite these predefined keywords meant to be as comprehensive as possible within the European context, these categories could be modified in order to fulfill specific needs of researchers related to geographical location, languages, or research questions.

Once a specific place is identified within a keyword for a pre-established category, the FLC estimates different indicators of relative distance to the LI. In particular, the FLC provides information on: (i) geographic distance (in kilometers) considering the road network using both Google API and OSM; (ii) the average time walking distance (in minutes), taking into account traffic density using Google API; and (iii) the average time cycling distance (in minutes), based on the traffic as well as road structure. As a main output, the FLC offers a detailed dataset for all the classified facilities located around each interest point. Figure 1 illustrates the process.

4. Final Remarks

The FLC can be used either as a main source of information or to complement traditional methods such as store census and official commercial lists, among others. It uses the most popular GIS search engines to assess the food environment, so this can be a source of potential errors because information could be either centrally generated by search engines or self-reported by facility owners/representatives. Despite the fact that all information is verified and standardized by the search engines, having self-reported information might lead to the following caveats: (i) the FLC will underestimate the food environment in places with low GIS information; (ii) the FLC will misallocate facilities in locations where no further information about the places is available. It is a very unlikely scenario as both sources of information have a very standardized method to collect this information.