# ArcGIS median value from layer?

I've been hunting around ArcGIS 9.3 and having no success at finding a tool/function that can give me the median (not the mean/avg) tabular value of a spatial database. For example, if I have a data layer of mountain peaks, I would like to be able to determine the elevation of #35 of 70 mountain peaks that exist within a county.

Conceptually it should be pretty easy. Count the total records, sort by elevation ascending, get the value from the elevation field for record # (count/2). Would I need to script this out in Python, or am I missing something obvious that would allow me get this more quickly? I find it hard to believe no one else has had a need for this function and created a solution.

To add some complexity to the matter, what if I wanted the median elev value for peaks in every county within the state in a single table? Basically the same output format as Frequency or Summary Statistics tools when using the Case Field option.

I was able to adapt the script linked by @VietThanh Le to meet my needs. I have posted the updated script and ArcToolbox at: http://resources.arcgis.com/gallery/file/geoprocessing/details?entryID=A0CD1751-1422-2418-882E-001EE0DC0D35

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would you consider updating your tool for use in 10.1? – Pat Johnson Jul 2 '13 at 20:29

I found a python script called Calculate Median Value in ArcScripts, but I have not tried it:

This script tool calculates the median value of one entire field and posts that single median value to every row in one other entire field.

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That's a great start, thanks. It doesn't quite have all the functions I am looking for (write to a standalone table, Case Field, etc) but the Python code to generate the median is what I really need, and should be able to code around that to make it fit my needs. I will repost the code and solution once I get it complete. – RyanDalton Jan 21 '11 at 17:25
resources.arcgis.com/gallery/file/geoprocessing/… contains other def's for various other stats which you might find useful – Dan Patterson Jan 21 '11 at 18:57