37 lines
1021 B
MySQL
37 lines
1021 B
MySQL
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--
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-- Calculate the equal interval bins for a given column
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--
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-- @param in_array A numeric array of numbers to determine the best
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-- to determine the bin boundary
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--
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-- @param breaks The number of bins you want to find.
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--
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--
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-- Returns: upper edges of bins
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--
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--
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CREATE OR REPLACE FUNCTION CDB_EqualIntervalBins ( in_array NUMERIC[], breaks INT) RETURNS NUMERIC[] as $$
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DECLARE
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diff numeric;
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min_val numeric;
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tmp_val numeric;
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i INT := 1;
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reply numeric[];
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BEGIN
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SELECT (max(e) - min(e)) / breaks::numeric, min(e) INTO diff, min_val FROM (SELECT unnest(in_array) e) x WHERE e is not null;
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RAISE NOTICE 'diff = %, min_val = %', diff, min_val;
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LOOP
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IF i < breaks + 1 THEN
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tmp_val = min_val + i::numeric * diff;
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RAISE NOTICE 'tmp_val = %', tmp_val;
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reply = array_append(reply, tmp_val);
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i := i+1;
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ELSE
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EXIT;
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END IF;
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END LOOP;
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RETURN reply;
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END;
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$$ language plpgsql IMMUTABLE;
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