Random % selection of data sample

[#1]

Question for the group on best approach and is it possible? If so how?

I have an app, with data loaded in memory.

I want the end user to be able to randomly select a % sample of the data without reloading it based upon a slider.

i.e If The app has 1000 records loaded into memory and the user decides they want a random sample of 30% of the data within the graphs, listboxes etc, they move the slider to 30% and the app selects the random 30% from memory.

Clicking back/clear resets the records to the full 1000 ...

Possible?

(I have the ability to do this on load , thanks to help from Gysbert and using Sample (n) already)

Robin.

[#2]

Further details (since Robin is helping me with this)

Using this article we were able to define a random sample within the app by manually entering an expression into the listbox:

QlikView Maven: Random Sample Selection

For example, =rand()<=0.2+now()*0

Rather than have to enter this each time, we'd like to have a slider that the user could adjust and have the random sample criteria be applied.  Example data is attached.

Thanks!

Ravi

[#3 · Accepted solution]

Hi,

Use trigger on a variable linked to a slider. Se attached example.

This is only working if you clear the account field before you use the slider.

Didn't get it to clear the field in the trigger... weird.

Cheers

[#4]

Thanks Martin.

[#5]

Splendid, thanks Martin!

[#6]

Apparently there isn't an OnClear trigger but a commonly suggested workaround is to add the trigger OnAnySelect and count the current selections.  If this is zero then the Clear button has been pressed.  I used this to set the variable behind the slider to 100%, see attached