Ordering a varlist in Stata code

Question

I see the following as a programming exercise, rather than a statistically grounded way of doing things.

Basically, I'd like to run N logistic regressions with one predictor variable and then for each variable store the variable name with its chi-squared value. After all predictions are done, I want to display each predictor variable ordered by chi-squared from highest to lowest.

So far I have the following:

local depvar    binvar1
local indepvars predvar1 predvar2 predvar3

* expand and check collinearity *
_rmdcoll `depvar' `indepvars', expand
local indepvars "`r(varlist)'"

* first order individual variables by best chi-squared *
local vars
local chis
foreach v in `indepvars' {
    di "RUN: logistic `depvar' `v'"
    quietly logistic `depvar' `v'

    * check if variable is not omitted (constant and iv) *
    if `e(rank)' < 2 {
        di "OMITTED (rank < 2): `v'"
        continue
    }

    * check if chi-squared is > 0 *
    if `e(chi2)' <= 0 {
        di "OMITTED (chi2 <= 0): `v'"
        continue
    }

    * store *
    local vars "`vars' `v'"
    local chis "`chis' `e(chi2)'"
    di "ADDED: `v' (chi2: `e(chi2)')"
}

* ... now sort each variable (from varlist vars) by chi2 (from varlist chis) ... * 

How would I sort each variable by the returned chi-square in the last line and then display the list of variables with their chi-squared ordered from highest chi-squared to lowest chi-squared?

To be clear, if the following varlists resulted from the above:

local vars predvar1 predvar2 predvar3
local chis 2 3 1

Then I would like to get something like the following:

local ordered predvar2 3 predvar1 2 predvar3 1

Or, alternatively,

local varso predvar2 predvar1 predvar3
local chiso 3 2 1

Answer 1

Here is one way to do it.

local depvar    binvar1
local indepvars predvar1 predvar2 predvar3

* expand and check collinearity *
_rmdcoll `depvar' `indepvars', expand
local indepvars "`r(varlist)'"

* first order individual variables by best chi-squared *

gen chisq = . 
gen vars = "" 
local i = 1 

foreach v in `indepvars' {
     di "RUN: logistic `depvar' `v'"
     quietly logistic `depvar' `v'

     * check if variable is not omitted (constant and iv) *
     if `e(rank)' < 2 {
          di "OMITTED (rank < 2): `v'"
     }

     * check if chi-squared is > 0 *
     else if `e(chi2)' <= 0 {
          di "OMITTED (chi2 <= 0): `v'"
     }

     * store *
     else {  
          quietly replace vars  = "`v'" in `i' 
          quietly replace chisq = -e(chi2) in `i' 
          local ++i   
          di "ADDED: `v' (chi2: `e(chi2)')"
     }
}

sort chisq
replace chisq = -chisq 
l vars chisq if chisq < ., noobs