Comment on page
Selecting a new restaurant location using Commercial Hotspots analysis

Context
Identifying an optimal location for a new store is not always an easy task, and we often do not have enough data at our disposal to build a solid model to predict potential revenues across an entire territory. In these cases, managers rely on different business criteria in order to make a sound decision for their expansion strategy. For example, they rely on defining their target market and segmenting population groups accordingly in order to locate the store closer to where the target market lives (e.g. areas with a great presence of youngsters).
In this tutorial, we are going to use CARTO’s Analytics Toolbox for BigQuery to explore good locations to open a new restaurant in Honolulu, Hawaii. For that, we will perform two different spatial analyses based on spatial indices (H3): Commercial Hotspots and Local Outlier Factor.
In-depth content and more technical information regarding the exercise found at Opening a new Pizza Hut location in Honolulu​
Steps to reproduce
1.Go to the CARTO signup page.
Click on Log in.
Enter your email address and password. You can also log in with your existing Google account by clicking Continue with Google.
Once you have entered your credentials: click Continue.
​
2.From the Navigation Menu in the left panel, select Maps. On the top-right corner, select “New map”. This should take you to a new instance of a Builder map:
3.We will define the overall Area of study by running an SQL query. Select the “Add source from…” at the bottom left of the page. Select the tab named “Custom Query (SQL)”, and click on the “CARTO Data Warehouse” connection:
4.We will write a custom SQL query, therefore select the “Type your own query” option and click on “Add source” on the bottom right. This should open the SQL Editor:
5.First we define the area of study by creating a buffer of 5km around Honolulu downtown. Run the query below:
SELECT ST_BUFFER(ST_GEOGPOINT(-157.852587, 21.304390), 5000) as geom
Rename the layer to “Area of Study”, and style the buffer according to the config seen below
6.We then extract our current store assets and display them on the map. In this example, we will extract Pizza Hut stores from a sample dataset including points of interest in Honolulu (subset of OpenStreetMaps’s Planet Nodes dataset). Add a new custom query, as we did in the buffer example, and introduce the query below:
 WITH buffer AS (
     SELECT ST_BUFFER(ST_GEOGPOINT(-157.852587, 21.304390), 5000) as geom
 )
    
 -- We identify all store locations within a 5 km buffer centered in Honolulu
 SELECT
 tag.value AS brand, d.geometry as geom,
 FROM
 `cartobq.docs.honolulu_planet_nodes` d,
 UNNEST(all_tags) as tag,
 buffer as b
 WHERE ST_CONTAINS(b.geom, geometry)
 AND ((tag.value in ("Pizza Hut") AND tag.key = 'brand'))
Rename the layer to “Own restaurant locations in Honolulu”, and style the buffer according to the config seen below
7.Next we will subdivide the area of study into H3 grid cells of resolution 10 using the query below:
CREATE TABLE `cartobq.docs.honolulu_pizza_aos` AS (
    SELECT h3
    FROM UNNEST(`carto-un`.carto.H3_POLYFILL(ST_BUFFER(ST_GEOGPOINT(-157.852587, 21.304390), 5000), 10)) h3
)
We have already created the table for you, named cartobq.docs.honolulu_pizza_aos. You only need to add a new custom query, and run the query below:
SELECT * FROM cartobq.docs.honolulu_pizza_aos
Ensure you select the spatial data type of the query as H3, on the top right hand side of the SQL Editor (see image).
Rename the layer “Polyfill area of study” and reorder the layer to it place as the bottom layer.
Hide the layer we have just created by clicking on the “eye” icon next to the 3 dots of each layer.
8.We will then enrich the H3 grid with population variables, with the aim of looking for areas with a high density of males and females between 15 and 34 years old. For more detailed analysis of how we do that you can refer to here, under the heading “Enrich area of study”.
We have already created the table for you, named cartobq.docs.honolulu_pizza_aos_enriched. You only need to add a new custom query, and run the query below:
SELECT * EXCEPT (h3id), h3id as h3 FROM cartobq.docs.honolulu_pizza_aos_enriched
Rename the layer “Demographics enriched area of study” and reorder the layer to place as the bottom layer. Hover over a hexagon to see that there is data on population of age groups.
Hide the layer we have just created by clicking on the “eye” icon next to the 3 dots of each layer.
9.Next, we aggregate all the population results (demographics per hexagon) and store into a single column.
DECLARE features ARRAY<STRING>;
DECLARE query STRING;
​
-- We get the names of all columns in the enriched table except for ('h3id')
SET features =
(
    SELECT ARRAY_AGG(column_name)
    FROM `cartobq.docs`.INFORMATION_SCHEMA.COLUMNS
    WHERE table_name = 'honolulu_pizza_aos_enriched' AND NOT column_name IN ('h3id')
);
​
SET query =
""" CREATE TABLE `cartobq.docs.honolulu_pizza_aos_enriched_sum` AS (SELECT h3id, """
|| ARRAY_TO_STRING(features, " + ")  ||
""" AS sum_pop FROM `cartobq.docs.honolulu_pizza_aos_enriched`)""";
​
-- We execute such query
EXECUTE IMMEDIATE query;
We have already created the table for you, named cartobq.docs.honolulu_pizza_aos_enriched_sum. You only need to add a new custom query, and run the query below:
SELECT * FROM cartobq.docs.honolulu_pizza_aos_enriched_sum
Rename the layer “Aggregated population” and reorder the layer to place as the bottom layer. Hover over a hexagon to see that there is now only one population value per hexagon (all the males and females 15 to 34).
Hide the layer we have just created by clicking on the “eye” icon next to the 3 dots of each layer.
10.In addition to the target population, we also want to consider the distance to the closest own store, in order to avoid cannibalization. To do this we calculate the distance of each hexagon to each store, and keep the minimum.
CREATE TABLE `cartobq.docs.honolulu_pizza_aos_enriched_sum_wdist` AS
(
WITH t1 AS (
    SELECT `carto-un`.carto.H3_FROMGEOGPOINT(geometry, 10) as h3id,
    FROM `cartobq.docs.honolulu_planet_nodes` d,
    UNNEST(all_tags) as tag
    WHERE ST_CONTAINS(ST_BUFFER(ST_GEOGPOINT(-157.852587, 21.304390), 5000), geometry)
    AND ((tag.value in ("Pizza Hut") AND tag.key = 'brand'))
),
 
t2 AS (
    SELECT * FROM `cartobq.docs.honolulu_pizza_aos_enriched_sum`
)
 
SELECT t2.h3id, ANY_VALUE(t2.sum_pop) AS sum_pop, MIN(`carto-un`.carto.H3_DISTANCE(t2.h3id, t1.h3id)) AS dist
FROM t1
CROSS JOIN t2
WHERE sum_pop IS NOT NULL
GROUP BY t2.h3id
);
We have already created the table for you, named cartobq.docs.honolulu_pizza_aos_enriched_sum_wdist. You only need to add a new custom query, and run the query below:
SELECT * EXCEPT (h3id), h3id as h3 FROM cartobq.docs.honolulu_pizza_aos_enriched_sum_wdist
Rename the layer “Demographics and distance to closest location” and reorder the layer to place below “Own restaurant locations” and “Area of study”. Hover over a hexagon to see that there is now one population value and distance value per hexagon (population between 15 and 34, and distance to closest own store).
Style the hexagons according to the config seen below, applying a gradient palette to represent with darker color the areas with the lowest population.
11.Next we will use the COMMERCIAL_HOTSPOTS method to identify locations with large populations aged 15-34 and far from existing own restaurants. This functionality identifies areas with values that are significantly higher than the average.
    CALL `carto-un`.carto.COMMERCIAL_HOTSPOTS(
        'cartobq.docs.honolulu_pizza_aos_enriched_sum_wdist',
        NULL,
        'h3id',
        'h3',
        ['sum_pop','dist'],
        [0.7, 0.3],
        2,
        0.01
    )
We have already created the table for you, named cartobq.docs.honolulu_pizza_hotspots. You only need to add a new custom query, and run the query below:
SELECT ST_UNION_AGG(`carto-un`.carto.H3_BOUNDARY(index)) AS geom FROM `cartobq.docs.honolulu_pizza_hotspots`
Rename the layer “Proposed restaurant locations” and reorder the layer to place below “Own restaurant locations” and “Area of study”.
Style the boundary according to the config seen below.
As we can see on the map, there are 7 regions identified as commercial hotspots, in 6 of which we currently have no store presence. These regions are achieving a high score in terms of concentration of age demographics between 15 and 34 (lighter areas), as well as long distance to other own stores.
We will then combine this information with another data point, competitors, to identify the hotspots with the lowest presence of competition.
12.We are going to extract competitors from the cartobq.docs.honolulu_planet_nodes table and compute the local outlier factor (using the LOF function) to identify those that are very close to one another and those far from the others.
-- We get all amenities tagged as restaurants or fast_food POIS in Honolulu
WITH fast_food AS (
    SELECT CAST(id AS STRING) AS id , tag.value, geometry as geom
    FROM `cartobq.docs.honolulu_planet_nodes` d,
    UNNEST(all_tags) as tag
    WHERE ST_CONTAINS(ST_BUFFER(ST_GEOGPOINT(-157.852587, 21.304390), 5000), geometry)
    AND ((tag.value in ('fast_food', 'restaurant') AND tag.key = 'amenity'))
),
 
-- We calculate the Local Outlier Factor in order to identify restaurants without competition.
lof_output as (
    SELECT `carto-un`.carto.LOF(ARRAY_AGG(STRUCT(id,geom)), 5) as lof FROM fast_food
)
SELECT lof.* FROM lof_output, UNNEST(lof_output.lof) AS lof
We have already created the table for you, named cartobq.docs.honolulu_competitors_lof. You only need to add a new custom query, and run the query below:
SELECT * EXCEPT (geo), geo as geom FROM `cartobq.docs.honolulu_competitors_lof`
Rename the layer “Competitor LOF analysis” and reorder the layer to place below “Own restaurant locations”.
Style the boundary according to the config seen below.
13.As we can see, the areas further south have a lot of competitors at close proximity to each other. However we can see a few minor clusters forming in the northern commercial hotspots. To identify the areas of very close proximity of competitors, we can filter by the local outlier factor score (LOF score). Scores higher than 1 indicate an outlier, while scores close to 1 indicate a non-outlier. To filter for the areas of high competition (i.e., where competitors are at very close proximity ), we should filter for scores below 1.2
We adapt the SQL query as such:
-- We get all amenities tagged as restaurants or fast_food POIS in Honolulu
WITH fast_food AS (
    SELECT CAST(id AS STRING) AS id , tag.value, geometry as geom
    FROM `cartobq.docs.honolulu_planet_nodes` d,
    UNNEST(all_tags) as tag
    WHERE ST_CONTAINS(ST_BUFFER(ST_GEOGPOINT(-157.852587, 21.304390), 5000), geometry)
    AND ((tag.value in ('fast_food', 'restaurant') AND tag.key = 'amenity'))
),
 
-- We calculate the Local Outlier Factor in order to identify restaurants without competition.
lof_output as (
    SELECT `carto-un`.carto.LOF(ARRAY_AGG(STRUCT(id,geom)), 5) as lof FROM fast_food
)
SELECT lof.* FROM lof_output, UNNEST(lof_output.lof) AS lof
WHERE lof.lof < 1.2
Or if you are querying directly from the cartobq.docs.honolulu_competitors_lof table
SELECT * EXCEPT (geo), geo as geom FROM `cartobq.docs.honolulu_competitors_lof`
WHERE lof < 1.2
Let´s investigate the result, seen below:
We can see that the 3 northernmost hotspots do not have any competitors visible, meaning there are no competitive clusters.
The combination of presence of target audience, remoteness from our own stores and competitor clusters make the 3 northernmost hotspots good candidates for expansion.
14.Change the name of the map to “Selecting a new restaurant location using Commercial Hotspots analysis”
15.Finally we can make the map public and share the link to anybody in the organization. For that you should go to “Share” on the top right corner and set the map as Public. For more details, see Publishing and sharing maps.
16.Finally, we can visualize the result.