1.1 KiB
1.1 KiB
Find the breaks for N categories in a numerical column based on the Jenks optimization. Below, Jenks used to color based on the area of the polygons.
Using the function
We can determine the 7 most optimal breaks in a column of numerical data as follows,
SELECT CDB_JenksBins(array_agg(numeric_column), 7) FROM table_name
-- Results in an ordered array like, {0,73,2568,9408,29411,768230,1638094}
-- Each break happens up to, and equal, to a number:
-- (bin1 is less than or equal to 0, bin2 is less than or equal to 73, etc.)
Arguments
CDB_JenksBins(in_array, breaks, invert)
- in_array numeric[]. A NUMERIC array of values.
- breaks int. The number of categories you want to create
- iterations OPTIONAL int. The number of iterations used for calculating breaks.
- invert OPTIONAL boolean. Flips whether you receive top down breaks or bottom up breaks. Default is top down (so, <=). Bottom up would give you values that define the lower-end start of a bin (so >=).