topic Re: points sampling in ArcGIS GeoStatistical Analyst Questions

points sampling

MilanBudhathoki1 — Thu, 19 May 2011 20:14:24 GMT

Hi everyone,

I have 35,000 points datasets. It is tedious to incorporate all points for my analysis. I am trying to generate random sample points in ArcGIS 9.3.1 platform. Is it possible run sampling technique in ArcGIS 9.3.1?

Thanks!

Re: points sampling

SteveLynch — Thu, 19 May 2011 21:13:51 GMT

Look at "Create Subsets" in 9.3
http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?id=4003&pid=3999&topicname=Extending_ArcMap_with_the_Geostatistical_Analyst_extension

or add a field to your dataset and use the "Calculate Field" GP tool using the following Python expression
arcgis.rand("Integer 0 100") (you'll have to modidy the 0 100)

or in ArcGIS 10, use the Subset Features GP tool

-Steve

Re: points sampling

MilanBudhathoki1 — Thu, 19 May 2011 22:01:56 GMT

Thank you Lynch !

Your instruction was handy.

Re: points sampling

MalenaVargas — Thu, 29 Mar 2012 22:39:21 GMT

I dont have Geoestatistical analyst and I want to make a random selection over points. I need help urgently!!!

Re: points sampling

TarunJaiswal — Thu, 29 Mar 2012 22:58:48 GMT

I dont have Geoestatistical analyst and I want to make a random selection over points. I need help urgently!!!

You can always get a 60 day trial version of Geostatistical Analyst.

Re: points sampling

EricKrause — Fri, 30 Mar 2012 16:01:09 GMT

You can also use Python's random number generator to get random subsets.

Let's say you have 100 points in your feature class, and you want a subset of 70 random points. Make a new Short Integer field in the feature class, then use Calculate Field. Make sure you change from VB to Python, and use this code:
arcgis.rand("Integer 1 100")

Then sort the Attribute table by the random number, and select the first 70 records.

Re: points sampling

SteveLynch — Fri, 30 Mar 2012 17:45:22 GMT

or you can read the post (05-19-2011 02:13 PM) in this thread

Steve