Defining value labels using variables in loop - how to extract the value of the nth observation of a variable within a group?

[Liz Broom]

Hi, I am trying to automate the definition of value labels using 3 variables within a dta: varname (the variable to be labelled), code (the variable value), parameter (the label). Once defined, I plan to use these to label a different dta. I struggling to automate the label definitions, I wondered if there was a way to save as a local the value of the nth observation of a specific variable within a group?

EXAMPLE DATASET:

clear
input str4 varname code str8 parameter
var1 1 label1_1
var1 2 label1_2
var1 3 label1_3
var1 4 label1_4
var1 5 label1_5
var1 6 label1_6
var2 0 label2_0
var2 1 label2_1
end

From this dataset I would want to save the following label lists:

label define var1labels 1 "label1_1" 2 "label1_2" 3 "label1_3" 4 "label1_4" 5 "label1_5" 6 "label1_6"
label define var2labels 0 "label2_0" 2 "label2_1"

I have an idea of how I can go about it, but it relies on me referring to the value of code and parameter that correspond to the nth observation within each group, which I'm unsure how to do. I also want to be able to extract the value of the varname variable corresponding to each group so that I can name my value label definition accordingly, allowing me to easily automate labelling later on.

egen grp = group(varname)
sort grp code
levelsof grp, local(groups)  // create local with all unique group values
egen grp_count = count(varname), by(grp) // count obs per grp
foreach grpnum of local groups { // loop through each vargrp
    count if grp == `grpnum'
    local grpcount = r(N)
    di "Group `grpnum'; Count: `grpcount'" // check working
    local list = "label define `grpnum'" // ideally want to extract varname value, not `grpnum'
    forval i = 1/`grpcount' {
//      local codeval = code[`i'] // something like this?
//      local parameterval = parameter[`i']
//      local list = `list' + " `codeval' `parameterval'" // planning to iteratively build the label definition
//      di "`list'"
    }
}

I'd be really grateful if anybody had any tips! Thank you so much in advance

[Chen Samulsion]

I recommend Roger Newson's -vallabdef- command which seems to perfectly tackle your problem.

clear
input str4 varname code str8 parameter
var1 1 label1_1
var1 2 label1_2
var1 3 label1_3
var1 4 label1_4
var1 5 label1_5
var1 6 label1_6
var2 0 label2_0
var2 1 label2_1
end

ssc install vallabdef

vallabdef varname code parameter

label list

. label list
var1:
           1 label1_1
           2 label1_2
           3 label1_3
           4 label1_4
           5 label1_5
           6 label1_6
var2:
           0 label2_0
           1 label2_1

[Hemanshu Kumar]

Hmm, here is a simple if somewhat wacky idea:

clear
input str4 varname code str8 parameter
var1 1 label1_1
var1 2 label1_2
var1 3 label1_3
var1 4 label1_4
var1 5 label1_5
var1 6 label1_6
var2 0 label2_0
var2 1 label2_1
end

sort varname code
gen varlabel = " " + string(code) + " " + parameter
gen varlabdef = ""
replace varlabdef = cond(varname == varname[_n-1], varlabdef[_n-1] + varlabel, varlabel)
by varname (code): replace varlabdef = cond(_n == _N, "label define " + varname + "label" + varlabdef, "")

which then can produce:

. list varlabdef if !missing(varlabdef), noobs sep(0)

  +------------------------------------------------------------------------------------------+
  |                                                                                varlabdef |
  |------------------------------------------------------------------------------------------|
  | label define var1label 1 label1_1 2 label1_2 3 label1_3 4 label1_4 5 label1_5 6 label1_6 |
  |                                             label define var2label 0 label2_0 1 label2_1 |
  +------------------------------------------------------------------------------------------+

. levelsof varlabdef, local(labdefs)
`"label define var1label 1 label1_1 2 label1_2 3 label1_3 4 label1_4 5 label1_5 6 label1_6"' `"label define var2label 0 label2_0 1 label2_1"'

[Nick Cox]

This may help as a fairly direct attack. Notice that I avoided the use of a local macro. See also https://journals.sagepub.com/doi/pdf...867X0600600313 and
https://journals.sagepub.com/doi/pdf...867X0600600414

clear
input str4 varname code str8 parameter
var1 1 label1_1
var1 2 label1_2
var1 3 label1_3
var1 4 label1_4
var1 5 label1_5
var1 6 label1_6
var2 0 label2_0
var2 1 label2_1
end

levelsof varname, local(myvars) clean

gen order = _n

foreach v of local myvars {
    levelsof code if varname == "`v'", local(myvals)  
    foreach c of local myvals {
        su order if varname == "`v'" & code == `c', meanonly
        label def `v' `c' "`=parameter[r(min)]'", modify
    }
}

label li

label save `myvars' using mylabels.do

type mylabels.do

Resulting do-file contains

label define var1 1 `"label1_1"', modify
label define var1 2 `"label1_2"', modify
label define var1 3 `"label1_3"', modify
label define var1 4 `"label1_4"', modify
label define var1 5 `"label1_5"', modify
label define var1 6 `"label1_6"', modify
label define var2 0 `"label2_0"', modify
label define var2 1 `"label2_1"', modify