label variable question and substr

[Yao Zhao]

Hi, I have several variables and their names are: q11r1_facebook q11r2_instagram q11r3_twitter q11r4_snapchat q11r5_pinterest q11r6_tiktok q11r7_linkedin q11r8_strava

I want to do

label variable q11r1_facebook "facebook"

. (The reason is that when I form the correlation table or regression table, I can read var labels.)

So I want to do:

foreach v of varlist q11r1_facebook-q11r8_strava {
    label variable `v' "???"
}

I guess it should use substr. Can anyone help me?

[Nick Cox]

Correct in so far that is a good way to do it.

foreach v of varlist q11r1_facebook-q11r8_strava {    
    local wanted = substr("`v'", strpos("`v'", "_")+ 1, .)      
    label variable `v' "`wanted'"
}

[Yao Zhao]

Great, thanks! Could you tell me what the meaning of +1 is?

[Nick Cox]

+ signifies addition. Suppose I have 2. Then I write 2 + 1. The meaning is 3.

I guess you know this really, So why here?

In this case, the function strpos() finds the position of the underscore, but then you should add 1 because you want to start with the character after the underscore.