topic Standard Deviation of columns if not zero (or null) in Python Questions https://community.esri.com/t5/python-questions/standard-deviation-of-columns-if-not-zero-or-null/m-p/1182376#M64756 <P>Hi, I'm trying to calculate the standard deviation of three column fields while ignoring zero (or null) values. I've tired various iterations of the expression code below but keep getting syntax errors.</P><P>statistics.stdev(d for d in (!ADFgal_2017_N!,!ADFgal_2018_N!,!ADFgal_2019_N!) if d != 0)</P> Mon, 13 Jun 2022 16:23:06 GMT gsmayes 2022-06-13T16:23:06Z Standard Deviation of columns if not zero (or null) https://community.esri.com/t5/python-questions/standard-deviation-of-columns-if-not-zero-or-null/m-p/1182376#M64756 <P>Hi, I'm trying to calculate the standard deviation of three column fields while ignoring zero (or null) values. I've tired various iterations of the expression code below but keep getting syntax errors.</P><P>statistics.stdev(d for d in (!ADFgal_2017_N!,!ADFgal_2018_N!,!ADFgal_2019_N!) if d != 0)</P> Mon, 13 Jun 2022 16:23:06 GMT https://community.esri.com/t5/python-questions/standard-deviation-of-columns-if-not-zero-or-null/m-p/1182376#M64756 gsmayes 2022-06-13T16:23:06Z Re: Standard Deviation of columns if not zero (or null) https://community.esri.com/t5/python-questions/standard-deviation-of-columns-if-not-zero-or-null/m-p/1182433#M64759 <P>try setting a definition query on the layer first to remove the null or "0" values.&nbsp; You may even have blank values that aren't showing up.</P> Mon, 13 Jun 2022 18:49:05 GMT https://community.esri.com/t5/python-questions/standard-deviation-of-columns-if-not-zero-or-null/m-p/1182433#M64759 ABishop 2022-06-13T18:49:05Z Re: Standard Deviation of columns if not zero (or null) https://community.esri.com/t5/python-questions/standard-deviation-of-columns-if-not-zero-or-null/m-p/1183525#M64776 <P>I can setup a definition query to keep only features where ADFgal_2017_N,&nbsp;ADFgal_2018_N, and ADFgal_2019_N are greater than zero but that's not really what I want. If there are greater than zero values in two columns and zero in a third, I want to calculate the standard deviation of the two values ignoring the zero value.</P> Thu, 16 Jun 2022 14:03:31 GMT https://community.esri.com/t5/python-questions/standard-deviation-of-columns-if-not-zero-or-null/m-p/1183525#M64776 gsmayes 2022-06-16T14:03:31Z