Using foreach numlist for more than one variable

[Anagaw Derseh]

Hello there,

Could you please let me know how can i use foreach numlist loop for more than one variable (let us say x1 x2 x3......) based on the following code?


foreach a of numlist 1 2 3 4 6 7 {

tab y x1 if x1= ‘a’

}

[Nick Cox]

Your syntax is illegal twice over, as you need a double equals sign to test for equality and a left-hand quote mark to open a macro reference:

foreach a of numlist 1 2 3 4 6 7 {
   tab y x1 if x1 == `a'
}

That said, experienced users would rewrite this as

forval a = 1/7 {
    tab y x1 if x1 == `a'
}

while noting that

tab y x1

or at most

tab y x1 if inrange(x1, 1, 7)

is likely to be what you want. If you have a specific reason for what you asked for, please tell us what it is.

From the characters you use, I fear that a word processor was used somewhere. The quote marks used by Stata are never curly.

PS After 2 years as a member and 20 posts, it's time to read the entire FAQ Advice, please, and to start using CODE delimiters.

[William Lisowski]

I agree with Nick that

tab y x1 if x1 == `a'

seems a very unlikely thing to want to do, since the result will be a tab with just one column for the single value of x1.

Building on Nick's answer, I am going to guess that the loop you wrote was your attempt to produce the following

tab y x1
tab y x2
tab y x3
tab y x4
tab y x5
tab y x6
tab y x7

which could be accomplished with

forvalues a = 1/7 {
    tab y x`a'
    }

Or, if x1-x7 are the only variables beginning with x,

foreach xvar of varlist x*  {
    tab y `xvar'
    }

[Nick Cox]

William Lisowski's guess is very interesting. Note for his case

tab2 y x1 x2 x3 x4 x5 x6 x7, firstonly 

gets you there in one.