From 2ad3ff547d3c4c0987702efdc40122ba8988136c Mon Sep 17 00:00:00 2001
From: Andy Eschbacher <eschbacher@cartodb.com>
Date: Thu, 7 May 2015 15:49:35 -0400
Subject: [PATCH] initial

---
 scripts-available/CDB_EqualIntervalBins.sql | 36 +++++++++++++++++++++
 1 file changed, 36 insertions(+)
 create mode 100644 scripts-available/CDB_EqualIntervalBins.sql

diff --git a/scripts-available/CDB_EqualIntervalBins.sql b/scripts-available/CDB_EqualIntervalBins.sql
new file mode 100644
index 0000000..2c2eadc
--- /dev/null
+++ b/scripts-available/CDB_EqualIntervalBins.sql
@@ -0,0 +1,36 @@
+--
+-- Calculate the equal interval bins for a given column
+--
+-- @param in_array A numeric array of numbers to determine the best
+--                   to determine the bin boundary
+--
+-- @param breaks The number of bins you want to find.
+--  
+--
+-- Returns: upper edges of bins
+-- 
+--
+
+CREATE OR REPLACE FUNCTION CDB_EqualIntervalBins ( in_array NUMERIC[], breaks INT) RETURNS NUMERIC[] as $$ 
+DECLARE 
+    diff numeric;
+    min_val numeric;
+    tmp_val numeric;
+    i INT := 1;
+    reply numeric[];
+BEGIN
+    SELECT (max(e) - min(e)) / breaks::numeric, min(e) INTO diff, min_val FROM (SELECT unnest(in_array) e) x WHERE e is not null;
+    RAISE NOTICE 'diff = %, min_val = %', diff, min_val;
+    LOOP
+        IF i < breaks + 1 THEN
+            tmp_val = min_val + i::numeric * diff;
+            RAISE NOTICE 'tmp_val = %', tmp_val;
+            reply = array_append(reply, tmp_val);
+            i := i+1;
+        ELSE
+            EXIT;
+        END IF;
+    END LOOP;
+    RETURN reply;
+END; 
+$$ language plpgsql IMMUTABLE;