Bikelanes Category Analysis (#71)

This PR implements an analysis on the distribution of the category
values of the `bikelanes` dataset. The results are saved in a separate
data set called `boundaryStats`. I've tested it with the OSM data of
Brandenburg and it finished within a few seconds.

.vscode/extensions.json

@@ -1,3 +1,6 @@
 {
-  "recommendations": ["sumneko.lua"]
+  "recommendations": [
+    "sumneko.lua",
+    "adpyke.vscode-sql-formatter"
+  ]
 }

app/analysis/boundaryStats.sql

@@ -0,0 +1,90 @@
+-- this function quantizes `LineStrings` into `Points` where each point represents a homogenous segment each of length  `res` +/- 25% (Note: segments shorter than `res` keep their length)
+CREATE OR REPLACE FUNCTION atlas_QuantizeLineString(ls Geometry(LineString), res numeric)
+    RETURNS TABLE(
+        len numeric,
+        geom Geometry(point)
+    )
+    AS $$
+DECLARE
+    len numeric := st_length(ST_Transform(ls, 25833));
+    n int := greatest(round(len / res), 1)::int;
+BEGIN
+    RETURN query
+    SELECT
+        len / n,
+        ST_LineInterpolatePoint(ls,(generate_series(1, n) - 0.5) / n::numeric) AS geom;
+END;
+$$
+LANGUAGE plpgsql;
+
+-- STEP 1: quantize bikelane data into points
+CREATE temp TABLE _bikelanesQuantized AS
+SELECT
+    osm_id,
+    tags,
+(atlas_QuantizeLineString(geom, 100)).* AS geom
+FROM
+    bikelanes;
+
+-- create a geospatial index on `_bikelanesQuantized` to speed up the spatial join;
+CREATE INDEX "_bikelanes_stats_geom_idx" ON _bikelanesQuantized USING gist(geom);
+
+-- STEP 2: calculate the distribution of our `category` for each area of the `boundary` data set
+-- make `osm_id` the primary of the `boundaries` table to allow selecting non-group-by columns
+ALTER TABLE boundaries
+    DROP CONSTRAINT IF EXISTS osm_id_key;
+
+ALTER TABLE boundaries
+    ADD CONSTRAINT osm_id_key PRIMARY KEY (osm_id);
+
+-- spatialy join `_bikelanesQuantized` with `boundaries` then group by category and boundaries.osm_id aggreagate the results in a single json object per area
+DROP TABLE IF EXISTS "boundaryStats";
+
+CREATE TABLE "boundaryStats" AS
+SELECT
+    osm_id,
+    geom,
+    region,
+    jsonb_object_agg(CONCAT(category, '_km'), len) AS bikelanes_category
+FROM (
+    SELECT
+        boundaries.osm_id AS osm_id,
+        boundaries.geom AS geom,
+        boundaries.tags ->> 'name' AS region,
+        _bikelanesQuantized.tags ->> 'category' AS category,
+        round(sum(_bikelanesQuantized.len) / 1000, 1) AS len
+    FROM
+        boundaries
+        JOIN _bikelanesQuantized ON ST_Intersects(boundaries.geom, _bikelanesQuantized.geom)
+    WHERE (boundaries.tags ->> 'admin_level')::int IN (4, 6, 7, 8)
+GROUP BY
+    boundaries.osm_id,
+    _bikelanesQuantized.tags ->> 'category') AS sq
+GROUP BY
+    osm_id,
+    geom,
+    region;
+
+DROP TABLE _bikelanesQuantized;
+
+-- this line is only for making pg_tileserve display the table
+SELECT
+    UpdateGeometrySRID('boundaryStats', 'geom', 3857);
+
+-- -- for `jsonb` with numeric values return a normalized object (all values sum to 100) which also includes the total value
+-- CREATE OR REPLACE FUNCTION atlas_NormalizeDistribution(dist jsonb)
+--     RETURNS jsonb
+--     AS $$
+-- DECLARE
+--     total numeric := sum(value)
+-- FROM (
+--     SELECT
+--         (jsonb_each(dist)).value::numeric) AS sq;
+-- BEGIN
+--     RETURN jsonb_object_agg(key, round((100 * value::numeric) / total, 2)) || jsonb_build_object('total', total)
+-- FROM (
+--     SELECT
+--         (jsonb_each(dist)).*) AS sq;
+-- END;
+-- $$
+-- LANGUAGE plpgsql;

app/run-5-analysis.sh

@@ -0,0 +1,8 @@
+#!/bin/bash
+set -e
+
+echo -e "\e[1m\e[7m Analysis – START \e[27m\e[21m\e[0m"
+
+psql -q -f "./analysis/boundaryStats.sql"
+
+echo -e "\e[1m\e[7m Analysis – END \e[27m\e[21m\e[0m"

app/run.sh

@@ -45,14 +45,18 @@ fi
 process_end_time=$(date +%s)
 export PROCESS_RUN_TIME_DIFF=$((process_end_time - process_start_time)) # used by metadata.sh
 
-if ! ./run-5-postprocess.sh; then
-    alert '*ERROR*: #run-5-postprocess exited with non-zero status code'
+if ! ./run-5-analysis.sh; then
+    alert '*ERROR*: #run-5-analysis exited with non-zero status code'
 fi
 
-if ! ./run-6-api.sh; then
-    alert '*ERROR*: #run-6-api exited with non-zero status code'
+if ! ./run-6-postprocess.sh; then
+    alert '*ERROR*: #run-6-postprocess exited with non-zero status code'
 fi
 
-if ! ./run-7-metadata.sh; then
-    alert '*ERROR*: #run-7-metadata exited with non-zero status code'
+if ! ./run-7-api.sh; then
+    alert '*ERROR*: #run-7-api exited with non-zero status code'
+fi
+
+if ! ./run-8-metadata.sh; then
+    alert '*ERROR*: #run-8-metadata exited with non-zero status code'
 fi