Drop variables with common suffix under certain conditions

[Stefano Grillini]

Dear all,

I am facing difficulties in dropping some variables conditional on the missing observations of one variable.
I have a dataset of prices, volumes and a measure of liquidity for 200 stocks. The dataset is a time series made of 601 variables, date, p1-p200, vo1-vo200 and liq1-liq200.
I want to drop p*, vo* and liq* if liq* has less than 30 observations.
I have tried

foreach var of varlist * {   
    qui count if missing(`var')     
    if r(N) >= 7535 drop `var'   
}

But there is a big problem with this approach. If let's say p1 has less than 30 but not vo1 than it drops p1 and keeps vo1.

Any suggestion?

Best

Stefano

[Nick Cox]

forval j = 1/200 {
       count if missing(liq`j')
       if r(N) >= 7535 drop p`j' vo`j' liq`j'
}

or

count if missing(p`j', vo`j', liq`j')

[Stefano Grillini]

Thank you very much Nick, I was kind of sure you'd have replied .

Best

Stefano

[Ina Diak]

Dear all, I am also facing difficulties in dropping observations of some 300 variables and 140 of them have a common suffix. All these 140 variables end by _xt and I want to drop observations for all the 300 variables if at least one the 140 variables ending by _xt has a value <= 5. The following command does not work : drop if *_xt <=5 . Thank you in advance!