Topic: How do selections work

[hyposmurf]

Dont have a clue yet how to create a lisp to do what I want to do, but Im hoping to understand some of the basics of selections.In order to grab similar objects from a drawing such as those on a certain layer,colour,linetype etc. Ive seen some lisps that do this by adding objects to selection sets.But can you just do this without creating a selection set,just have autocad search its database and then select the items.Like for instance the QSELECT command will do this,no need to create your selection sets or groups.Problem with the QSELECT, is that its slow to open and run through all the parameters you need.Id like to be able to run something similar to it at the command line.Could then run a number of different lisps or macros for each type of selection.

[paulmcz]

This will select all red circles in entire drawing and asign to variable "a".

Code: [Select]

(setq a (ssget "x" '((0 . "circle")(62 . 1))))

[Kerry]

To be precise, that is not semantically correct.

using filter (62 . 1) indicates color property set to 1<acred> . If the object color is BYLAYER on a RED layer it will not be filtered.

.. I realise the distinction seems minor, but the difference can be irritating when selections do not happen as you'd "expect" 

[Kerry]

Without knowing the level of your current knowledge, it's difficult answer your "I'd like ... "
I think you'd need to create a selection set, then use "Prev" for selection in commands .. Yes ?

There's a fair bit to it, so,
Have a look in the Help file at :

ssget
Selection Set Handling
Selection Set Filter Lists 
Relational Tests

[paulmcz]

To be precise, that is not semantically correct.

using filter (62 . 1) indicates color property set to 1<acred> . If the object color is BYLAYER on a RED layer it will not be filtered.

.. I realise the distinction seems minor, but the difference can be irritating when selections do not happen as you'd "expect" 

I agree!

[hyposmurf]

Without knowing the level of your current knowledge, it's difficult answer your "I'd like ... "
I think you'd need to create a selection set, then use "Prev" for selection in commands .. Yes ?

There's a fair bit to it, so,
Have a look in the Help file at :

ssget
Selection Set Handling
Selection Set Filter Lists 
Relational Tests

My current knowledge of all things lisp related is quite honestly poor .I can modify lisps and can sometimes work out whats going in each lisp.Im slowly picking up the very basics but its not a fast process.Thanks for those Kerry I'll go and have a look.

[Kerry]

'Smurf,

also, have a play with the SSX command .. and have a look at the source in the ACAD support folder ..

[CAB]

hyposmerf
Go Here   http://www.smadsen.com/
and in the left column look under "Selections"
See "By Code" & "Filters"
There is a lot of information on using ssget.
It is a powerful tool when you learn to use the filters.

[David Bethel]

Hypo,

Here's one I've have used for ages, it allows for selectiobn sets with filters and then editing by dxf group code of a selection set.

http://www.davidbethel.com/cadtutor/ssedit.lsp

It is based on native R12 entity types but can be pretty powerful ( read dangerous )  -David

[uncoolperson]

if you're wanting things to be selected and passed between this and that without passing a selection set variable deally look into

Code: [Select]

(sssetfirst gripset [pickset])