From 0b94cc68cec11d97fcdf0891d609a7885db91cd3 Mon Sep 17 00:00:00 2001
From: tara <tara@gfz-potsdam.de>
Date: Tue, 19 Apr 2022 11:50:14 +0200
Subject: [PATCH] added update_tile_table & alter_table funcs to
 boundary_comparison.py

---
 boundarycomparator/boundary_comparator.py | 60 ++++++++++++++++++++++-
 1 file changed, 59 insertions(+), 1 deletion(-)

diff --git a/boundarycomparator/boundary_comparator.py b/boundarycomparator/boundary_comparator.py
index 40316d4..91483f8 100644
--- a/boundarycomparator/boundary_comparator.py
+++ b/boundarycomparator/boundary_comparator.py
@@ -8,7 +8,7 @@ logger.setLevel(logging.DEBUG)
 logger.addHandler(logging.StreamHandler(sys.stdout))
 
 
-# Connecting to the exposure database using `exposurelib`.
+# Connecting to the exposure database using `exposure-lib`.
 def connect_to_exposure_database(
     exposure_database_filepath, spatialite_filepath="mod_spatialite.so"
 ):
@@ -47,6 +47,13 @@ def create_tables(exposure_db):
     logger.info("Table Stats created")
 
 
+# Adds a field to the table `Tile` to be later fed by the function `update_tile_table`
+def alter_table(exposure_db, table_name, field_name, field_type):
+    sql_statement = "ALTER TABLE %s " "ADD %s %s" % (table_name, field_name, field_type)
+    exposure_db.connection.execute(sql_statement)
+    return exposure_db
+
+
 # Attaches to a GeoPackage boundary file and copies over the boundaries and their names
 # and IDs to the table `Boundary`
 def import_districts_and_boundaries(
@@ -163,6 +170,55 @@ def insert_into_stats(exposure_db):
     exposure_db.connection.commit()
 
 
+# Insert the sum of number of assets per tile, for the `exposure_db`
+def update_tile_table(exposure_db, field_name):
+    """
+    Inserts the summation of number of buildings per tile of the `exposure-db` (Please note
+    that this summation is only for the boundary which the `exposure-db` is distributed
+    over)
+
+    Args:
+        exposure_db (database):
+            The exposure database to which the results should be written (into the table
+             `Tile`)
+        field_name (str):
+            Name of the field to which the new data should be inserted
+
+    The innermost query, selects tile IDs and summation of number of buildings
+    (named `tot_num_buildings`) per each `tile_id` from `TileAsset` table.
+
+    Example extract:
+
+    tile_id             tot_num_buildings
+    120233333333010231	0.74128
+    120233333333010233	0.74128
+    120322222222121233	0.97302
+    ...
+    The middle query, selects only the `tot_num_buildings` field.
+    The outermost query, adds the `tot_num_buildings` to the respective
+    `field_name` in the table `Tile` mathing the tile IDs already in the table.
+    """
+
+    sql_statement = (
+        """
+        UPDATE Tile
+        SET %s =
+        (
+            SELECT tot_num_buildings FROM
+                (
+                SELECT tile_id, sum(TileAsset.number) AS tot_num_buildings
+                FROM TileAsset
+                GROUP BY tile_id
+                )
+            WHERE tile_id =  Tile.id
+        )
+        """
+        % field_name
+    )
+    exposure_db.cursor.execute(sql_statement)
+    exposure_db.connection.commit()
+
+
 def main():
     exposure_database_filepath = (
         "../inputs/Attica/exposure/M023_exposure_Attica_GDE_" "cellspart_v005_ghs_Ind.db"
@@ -174,6 +230,8 @@ def main():
     import_districts_and_boundaries(exposure_db, gadm_boundaries_gpkg_filepath, 0)
     import_districts_and_boundaries(exposure_db, osm_boundaries_gpkg_filepath, 1)
     insert_into_stats(exposure_db)
+    alter_table(exposure_db, "Tile", "tot_num_buildings_per_tile", "REAL")
+    update_tile_table(exposure_db, "tot_num_buildings_per_tile")
 
 
 if __name__ == "__main__":
-- 
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