Understanding the delete sop

[nas7ybuttler]

In my sample file here I have a box copied onto 5 points of a line, each box with it's own group. I eventually want to delete the middle box (group 2) when an expression I specify returns true. I thought I knew how to do this, but in a preliminary test my method didn't work. Here is what I did:

1) specify group 2 in the group field

2) use 'delete selected'

3) entity primitives

4) Operation 'delete by expression' (default is 0)

This is where the behaviour gets a bit strange. When I have the value of 'delete by expression' set at 0, it deletes the second box. WHen it is 1, it deletes ALL boxes. The first result is the opposite of what I would expect (I expected it to only delete when the value is non-zero), and the second result doesn't seem like it should occur, since I used the group field to limit the sop to a subset of the input geometry. Any ideas on what i'm doing wrong?

delete_test.hipnc

[anim]

it seems to me that group field is used as an addition to other filters

so when you disable other methods you can clearly see the effect

now, when you enable expression and type 0, it means, select none, but in group field there is your group 2 so it will select group 2 and delete

when your expression is 1, it will select all primitives/points + group 2 in group field which results in all primitives/points

if you want to delete group 2 and only if expression occurs, you have to type both in expression field

example file: deletes group 2 if current frame < 10

delete_test2.hipnc