Qliksense Button to toggle every 20th time stamp (subsampling the data)

[padmanabhv]

Hello,
Lets say I have a large data set - with  data collected every 15 seconds - 00:00:15, 00:00:30
I also have timestamps number 1,2, etc corresponding with each timestamp
1 - 00:15
2- 00: 30 , etc

I need to sub-sample to every 20th sample, using a button and I cannot figure out the what to put under 'Value' within Button > actions > Togglefield selection ?
There has to be some formula using mod that should get me what I need.
Thank you for your help !!

[padmanabhv]

I put a hacky - '= '(1|21|41|61|81|101|121|141|161|181|201|221|241|261|281|301|321|341|361|381|401|421|441|461|481|501|521|541|561|581|601)' in the value box, to take in every 20th sample
But there has to be a more elegant way

[Levi_Turner]

My gut approach would be to off-load this to a counter in the script. That'll be far more maintainable and more performant.

Let's take a table which I mocked up:

[table]:
LOAD 
	RowNo() AS [Hour]
AutoGenerate 24;

LEFT JOIN([table])
LOAD
	RowNo() AS [Minute]
AUTOGENERATE 60;

LEFT JOIN([table])
LOAD
	RowNo() AS [Second]
AUTOGENERATE 60;

RENAME TABLE [table] TO [tmp];

[table]:
NoConcatenate
LOAD
	RowNo() AS [id],
    *
RESIDENT [tmp];

DROP TABLE [tmp];

From there, we can build a counter like so:

[table]:
NoConcatenate
LOAD
	*,
	if(Mod(Frac(([id]-1)/20),1)=0 OR [id]=1,1,0) AS [Counter];
LOAD
    [id],
    [Hour],
    [Minute],
    [Second]
RESIDENT [tmp];

DROP TABLE [tmp];

To walk through the counter,

• Set 1 for the counter if the id = 1 (aka the first record)
• For all subsequent records: 
  • Subtract 1 (i.e. 21 -> 20)
    • ([id]-1)
  • Divide  by 20 (i.e. 20 / 20)
    • ([id]-1)/20)
  • Take the fraction of that value (i.e, 20 / 20 = 1, fraction = 0)
    • Frac(([id]-1)/20)
  • Perform a modulo function on this value  (i.e 0 / 1 = 0)
    • Mod(Frac(([id]-1)/20),1)
  • If that return is 0 then evaluate as true, else it's false