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Convert CDB_EqualIntervalBins to a single SQL statement and add float version

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This commit is contained in:
Paul Norman 2016-04-20 16:07:00 -07:00
parent 1358964628
commit b19a5fc3dc
1 changed files with 19 additions and 25 deletions
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44
scripts-available/CDB_EqualIntervalBins.sql
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@ -1,7 +1,7 @@
--
-- Calculate the equal interval bins for a given column
--
-- @param in_array A numeric array of numbers to determine the best
-- @param in_array A numeric or double precision array of numbers to determine the best
-- to determine the bin boundary
--
-- @param breaks The number of bins you want to find.
@ -10,28 +10,22 @@
-- Returns: upper edges of bins
--
--
CREATE OR REPLACE FUNCTION CDB_EqualIntervalBins ( in_array NUMERIC[], breaks INT ) RETURNS NUMERIC[] as $$
DECLARE
diff numeric;
min_val numeric;
max_val numeric;
tmp_val numeric;
i INT := 1;
reply numeric[];
BEGIN
SELECT min(e), max(e) INTO min_val, max_val FROM ( SELECT unnest(in_array) e ) x WHERE e IS NOT NULL;
diff = (max_val - min_val) / breaks::numeric;
LOOP
IF i < breaks THEN
tmp_val = min_val + i::numeric * diff;
reply = array_append(reply, tmp_val);
i := i+1;
ELSE
reply = array_append(reply, max_val);
EXIT;
END IF;
END LOOP;
RETURN reply;
END;
$$ language plpgsql IMMUTABLE;
WITH stats AS (
SELECT min(e), (max(e)-min(e))/breaks AS del
FROM (SELECT unnest(in_array) e) AS p)
SELECT array_agg(bins)
FROM (
SELECT min + generate_series(1,breaks)*del AS bins
FROM stats) q;
$$ LANGUAGE SQL IMMUTABLE;
CREATE OR REPLACE FUNCTION CDB_EqualIntervalBins ( in_array double precision[], breaks INT ) RETURNS double precision[] as $$
WITH stats AS (
SELECT min(e), (max(e)-min(e))/breaks AS del
FROM (SELECT unnest(in_array) e) AS p)
SELECT array_agg(bins)
FROM (
SELECT min + generate_series(1,breaks)*del AS bins
FROM stats) q;
$$ LANGUAGE SQL IMMUTABLE;