topic Re: Round values in an attribute table to the nearest nth value using the Field Calculator and a Python expression. in Python Questions

Round values in an attribute table to the nearest nth value using the Field Calculator and a Python expression.

KelvinMwakomo — Wed, 02 Mar 2016 06:19:47 GMT

Hello guys

I want to use the Field Calculator in ArcMap to round an existing column to two decimals. Currently I have a column (AREA_Ha) that is 3 decimal places long and would like to simply round it down to 2 decimals.

I have tried this ( round(!AREA_Ha!, 2)) but get this error message " There was a failure during processing, check the Geoprocessing Results window for details.

Your help please.

Re: Round values in an attribute table to the nearest nth value using the Field Calculator and a Python expression.

DanPatterson_Retired — Wed, 02 Mar 2016 10:24:21 GMT

that is because your area field was made into a string.

You can tell because it is left justified and contains 'ha' at the end. So however you created the area field wasn't a true area field but the representation of an area field.

The most descriptive is to follow

a = '1.2345 ha'

round(float(a.split(" ")[0]),2)

yields 1.23

where 'a' is your field name

Re: Round values in an attribute table to the nearest nth value using the Field Calculator and a Python expression.

KelvinMwakomo — Wed, 02 Mar 2016 12:02:43 GMT

Thanks Dan but is to possible to add the unit abbreviation eg.1.23 Ha

Re: Round values in an attribute table to the nearest nth value using the Field Calculator and a Python expression.

DanPatterson_Retired — Wed, 02 Mar 2016 12:19:30 GMT

str(round(float(a.split(" ")[0]),2) ) + " ha"

but it is getting ridiculously convoluted, the area calculation should have been sent to a numeric field, rounding there, and then, converted to string in a subsequent field

Re: Round values in an attribute table to the nearest nth value using the Field Calculator and a Python expression.

KelvinMwakomo — Wed, 02 Mar 2016 12:32:35 GMT

Thanks Dan for your assistance