Vector Layer group by properties

Question

I brought in a vector shapefile with around a total of 20 different pressures. I want to make this vector into two different shapefiles. One for the property "Pressure" of lines that have under 20 pressure and another for the same property that has a pressure of 20 and over. I know of the Vector > Split Vector Layer command but that splits the one shapefile into 20 different ones.

Answer 1

I would probably do the following:

1. Use the Field Calculator to create a new field and then use an expression like:

   if( "Pressure" < 20, 0, 1 )
   

   This will add a '0' to all features with a pressure value less than 20, otherwise will it will add a '1'.

---

2. Run the Vector > Data Management Tools > Split Vector Layer tool and select the new field to produce two shapefiles.

Answer 2

Select all the lines with a pressure < 20 and then save it to a new file making sure to check save only selected features.

Then invert the selection (look in the selection expression menu) and then save again.