I'm pretty new to GIS in general and I'm trying to take an absolute value of the difference between two fields in field calculator when creating a new field, but using ABS () returns an invalid expression in Preview. ABS () is not listed on the supported expressions--is there a way around this? Thanks! John
You seem to use QGIS 1.8, because the development version (soon to be 2.0) supports abs().
Instead, you can use
... replace value with your attribute.