Cards vs Listfield/custom properties revisited

[Lars Brehmer]

I followed the discussion about using stacks of many cards vs. a  
listfield vs. a custom property vs. a database.

I use a data stack with around 5,000 cards with anywhere from 4 or 5  
to over a hundred custom properties in each (out of 250 possible), so  
I decided to try everyone's advice.  I created a custom property with  
1 line with up to 250 items for each of the data cards.

My first speed tests were quite promising at first (example: what took  
1765 milliseconds the card way took just 60 milliseconds the new way.)  
Being a non coder type (please be patient with my lack of expertice),  
I haven't been able to find ways to translate all of the search and  
sort operations I do. Most things rely on the very basic

mark cards where some custom property = some condition
lock screen
lock messages --the data stack has an openCard handler that affects my  
main stack
repeat for q = 1 to the num of marked cards
go next marked card
do something
end repeat
unmark all cards
--mark cards the way they were before this operation
unlock messages
unlock screen

While this has always been fast enough for me, I am trying to learn  
better ways to do things, but after trying such things as filter with  
or match etc, I have found no way do something that has the same  
result as "mark cards where ...". Is there anything that would have  
the effect of the (apparently not possible) command "mark lines in it  
where ..."? I suppose it would look something like this:

put the mData of this stack into gData --loads that big custom prop
somehow get rid of lines where something is not in a certain item of  
those lines
set the tempData of this stack to gData
do things with the tempData of this stack

I have been fiddling with this in my amateurish way for a couple of  
days now, and would really appreciate a simple to understand push in  
the right direction.

Cheers,


Lars