* version 1.0.1 Jan 2019
* Author Fernando Rios Avila
* This is a program that can be used as a "mask" for Oaxaca, allowing to do RIF recomposition
* Various RIF decompositions are available. More than just RIFREG
* Correction to output table regarding Reweight error.
capture program drop oaxaca_rif
program oaxaca_rif, eclass
    if replay() {
        display_ob
        exit
    }
	version 12.0
   syntax anything [if] [in] [aw fw iw pw] , by(varname) rif(string)   [ swp swap Weights(str) rwlogit(varlist) rwprobit(varlist) wgt(int -1) cluster(varname) ]
   ** This reads the variables used  for the model
   *if "`anything'"=="" & "`options'"=="" {
   *    ereturn display
   * }
	
	tokenize `anything'
	local y `1'
	//get the rest of the vars
	macro shift
	local rest `*'
	marksample touse
 
	foreach i in `anything' `by' `rwlogit' `rwprobit' {
		capture replace `touse'=0 if `i'==.
	}
	
	****Here we identify GROUPs
	qui:levelsof `by' if `touse', local(idf)
	foreach i of local idf {
	   local nx=`nx'+1
	   local g`nx'=`i'
	   if `nx'>2 {
			display "More than 2 groups in `by' identified. Only 2 groups can be used"
			exit
	   }
	}
	
	** Get weights
    if "`weight'" == "" {
	 tempvar eweight
         gen `eweight' = 1.0
         local weight "aweight"
         local exp `eweight'
		 local erweight 1
     }
    else {
		local exp = regexr("`exp'", "= ", "")
	    local erweight `exp'
	 	}
	 
 
      //get the weight expression without '=' sign
      local exp_no_eq = regexr("`exp'", "=", "")
	*** This is to check if weights was called isntead of WGT
	if "`weights'"!="" {
	local wgt=`weights'
	local weights=""
	}
	*** This should check if cf is 0 or 1, or use the default 0
    
	if "`wgt'"=="-1" {
	display "No wgt specified. Using default 0"
	local wgt = "0"
	}
 
	if "`wgt'"!="0" & "`wgt'"!="1" {
	display "For Weighted Oaxaca, one can only use w=1 or w=0"
	exit 
	} 
	****
	if "`rwlogit'"!="" & "`rwprobit'"!="" {
	display "Only one probability model can be set. Choose either Logit or probit for the first stage"
	exit
	}
    ****
	if "`rwlogit'"=="" & "`rwprobit'"=="" {
	display "No Reweighted Strategy Choosen"
	local type="Standard"
	}
	else {
	local type="Reweighted"
	}
	***
	* checking for swap
	if "`swap'"!="" {
	    local swap=""
		local swp="swp"
	}
	
	display "Estimating `type' RIF-OAXACA using RIF:`rif'"
	
	
	*** Option 1. Standard oaxaca
	if "`type'"=="Standard" {
	preserve
	    if "`swp'"!="" {
		replace `by'=-`by'
		 local gx=`g1'
		 local g1=`g2'
		 local g2=`gx'
		}
		************************************************************
		/*no longer need rifreg. All is estiamted using rifvar
		 qui:levelsof `by' if `touse'==1, local(grps)
		 qui:capture drop rif_`y'
		 qui:gen double rif_`y'=. 
        if "`rif'"=="mean" {
		   qui:replace rif_`y'=`y'	
		}
		else {    
			foreach i of local grps {
				capture drop rx
				 qui:rifreg `y' [`weight'=`exp'] if `touse'==1 & `by'==`i', `rif' retain(rx)
				 qui:replace rif_`y'=rx  if `touse'==1 & `by'==`i'
			}
		}*/
 		qui: egen rif_`y'=rifvar(`y') if `touse'==1, `rif' weight(`exp') by(`by')
		*noisily: tabstat  rif_`y', by(`by') stats(n mean)
 		local re rif_`y' `rest'
		*qui:reg `re' if `touse'==1
		qui:oaxaca `re' [`weight'=`exp'] if `touse'==1,   by(`by') w(`wgt') robust cluster(`cluster')
 
		drop rif_`y'
		local lgd `e(legend)'
		matrix b=e(b)
		matrix V=e(V)
		if `wgt'==0 {
			local gc = "x1*b2"
		}
		if `wgt'==1 {
			local gc = "x2*b1"
		}
		local N1=e(N_1)
		local N2=e(N_2)
		
		*************************************************************
	restore
	}
	
	if "`type'"=="Reweighted" {
	************************************************************
	preserve
		qui:keep if `touse'==1
		if "`swp'"!="" {
		 qui:replace `by'=-`by'
		 local gx=`g1'
		 local g1=`g2'
		 local g2=`gx'
		}
		** For this application, we need to duplicate One of the groups, to create the counterfactual.
		qui:levelsof `by' if `touse'==1, local(grps)
		tempvar dy
		qui:egen `dy'=group(`by')
		qui:sum `dy'
		***
		if r(max)>2 {
		  display "More than 2 groups detected. Only 2 groups allowed for reweighted OAXACA"
		  exit
		}
		qui:replace `dy'=`dy'==2
		
		** Here we do the probit/logit regression
		if "`rwprobit'"!="" {
			qui:probit `dy' `rwprobit' [pw=`exp'] if `touse'==1
			tempvar pr
			qui:predict double `pr', pr
			matrix b_rw=e(b)
			matrix v_rw=e(V)
			local rwmodel="probit"
		}
		if "`rwlogit'"!="" {
			qui:logit `dy' `rwlogit' [pw=`exp'] if `touse'==1
			tempvar pr
			qui:predict double `pr', pr
			matrix b_rw=e(b)
			matrix v_rw=e(V)
			local rwmodel="logit"
		}
		*** Here we will expand the data according to W and create new groups
		*** and create the IPW weights
		if `wgt'==0 {
		 * display "Counterfactual: group_2 reweighted to group_1 characteristics"
		  tempvar id ord
		  qui:gen `id'=_n
		  qui:expand 2 if `dy'==1
		  
		  qui:bysort `id':gen `ord'=_n
		  tempvar ddy
		  qui:gen  byte   `ddy'=1 if `dy'==0
		  qui:replace `ddy'=3 if `dy'==1 
		  qui:replace `ddy'=2 if `dy'==1 & `ord'==1
		  
		  tempvar ipw
		  qui:gen double `ipw'=1 if `ddy'==1 |  `ddy'==3 
		  qui:replace `ipw'=(1-`pr')/`pr' if  `ddy'==2
 		  local gc="X2~>rw~>X1"
		}
		if `wgt'==1 {
		 * display "Counterfactual: group_1 reweighted to group_2 characteristics"
		  tempvar id ord
		  qui:gen `id'=_n
		  qui:expand 2 if `dy'==0
		  qui:bysort `id':gen `ord'=_n
		  tempvar ddy
		  qui:gen  byte   `ddy'=1 if `dy'==0
		  qui:replace `ddy'=3 if `dy'==1
		  qui:replace `ddy'=2 if `dy'==0 & `ord'==1
		  tempvar ipw
		  qui:gen double `ipw'=1 if `ddy'==1 |  `ddy'==3 
		  qui: replace `ipw'=`pr'/(1-`pr') if `ddy'==2
 		  local gc="X1~>rw~>X2"
		}
		qui:compress
		*** Here we create the RIFs using RIFreg for three groups. group 2 its the Counterfactual.
        tempvar rifvar
		/*
		if "`rif'"=="mean" {
		qui:gen double `rifvar'=`y'	
		}
		else {
			qui:levelsof `ddy' if `touse'==1, local(grps)
			qui:gen double `rifvar'=.
			tempvar rx
			foreach i of local grps {
				capture drop `rx'
				qui:rifreg `y' [`weight'=`exp'] if `touse'==1 & float(`ddy')==`i', `rif' retain(`rx')
				qui:replace `rifvar'=`rx'  if `touse'==1 & float(`ddy')==`i'
				** add additional matrices to save results
			}
		}
		*/
		qui:egen `rifvar'=rifvar(`y') if `touse', `rif' weight(`exp') by(`by')
 
        *** Here we do the actual OB decomposition: 
 		local re `rifvar' `rest' 
		if "`cluster'"!="" 	local idcluster `cluster'
		else 				local idcluster `id'
		 
		
  		qui:oaxaca `re' [aw=`exp'*`ipw'] if `touse'==1 & (`ddy'==1 | `ddy'==3),   by(`ddy') w(`wgt') nodetail robust cluster(`idcluster')
 
        matrix b0=e(b)
        matrix v0=e(V)  
		if `wgt'==0 { 
		   ** Delta B
	 		qui:oaxaca `re' [aw=`exp'*`ipw'] if `touse'==1 & inlist(`ddy',1,2),   by(`ddy') w(0) cluster(`id') 
			matrix bb=e(b)
			matrix vb=e(V)
		   ** Delta x
			qui: oaxaca `re' [aw=`exp'*`ipw'] if `touse'==1 & inlist(`ddy',2,3),   by(`ddy') w(0) cluster(`id')
			matrix bx=e(b)
			matrix vx=e(V)
			local lgd `e(legend)'
			
			matrix bc=bx[1,1]
			matrix vc=vx[1,1]
			}
		if `wgt'==1 {
		   ** Delta X
			qui:oaxaca `re' [aw=`exp'*`ipw'] if `touse'==1 & inlist(`ddy',1,2),   by(`ddy') w(1) cluster(`id')
			matrix bx=e(b)
			matrix vx=e(V)
		   ** Delta B
			qui:oaxaca `re' [aw=`exp'*`ipw'] if `touse'==1 & inlist(`ddy',2,3),   by(`ddy') w(1) cluster(`id')
			matrix bb=e(b)
			matrix vb=e(V)
			local lgd `e(legend)'
			matrix bc=bx[1,2]
			matrix vc=vx[2,2]
			}
		qui:count if `touse'==1 & `ddy'==1  
		local N1=r(N)
		qui:count if `touse'==1 & `ddy'==2
		local NC=r(N)
		qui:count if `touse'==1 & `ddy'==3
		local N2=r(N)
		** This next section gets all the betas of interest
		** Aggregate Decomp
		matrix b0=b0[.,"overall:group_1"],bc,b0[.,"overall:group_2"],b0[.,"overall:difference"]
		matrix v0=v0[.,"overall:group_1"],[0,0,0,0,0]',v0[.,"overall:group_2"],v0[.,"overall:difference"]
		matrix v0=v0["overall:group_1",.]\[0,vc,0,0]\v0["overall:group_2",.]\v0["overall:difference",.]
	 
        **Explained 
		matrix bx1=bx[.,"overall:"]
		matrix bx2=bx[.,"explained:"]
		matrix bx3=bx[.,"unexplained:"] 
		matrix coleq   bx1="Explained"
		matrix colname bx1=Group_1 Group_2 Total True_explained Specif_err
		matrix coleq   bx2="True_explained"
		matrix coleq   bx3="Specif_err"
		matrix bx=bx1[.,3...],bx2,bx3
        matrix drop bx1 bx2 bx3
		matrix vx=vx[.,3..5],vx[.,"explained:"],vx[.,"unexplained:"]
		matrix vx=vx[3..5,.]\vx["explained:",.]\vx["unexplained:",.]

		**unexplaiend
		matrix bb1=bb[.,"overall:"]
		matrix bb2=bb[.,"explained:"]
		matrix bb3=bb[.,"unexplained:"] 
		matrix coleq   bb1="Unexplained"
		matrix colname bb1=Group_1 Group_2 Total  Reweight_err True_Unexplained
		matrix coleq   bb3="True_Unexplained"
		matrix coleq   bb2="Reweight_err"
		matrix bb=bb1[.,3...],bb3,bb2
		matrix drop bb1 bb3 bb2
		matrix vb=vb[.,3..5],vb[.,"unexplained:"],vb[.,"explained:"]
		matrix vb=vb[3..5,.]\vb["unexplained:",.]\vb["explained:",.]
		**Label VCOV to extract Total Explained and Total unexplained.
		noisily display "HERE"
		**Putting all together
		*For Beta0
		matrix b0=b0,bx[.,"Explained:Total"],bb[.,"Unexplained:Total"] 
		matrix coleq b0=Overall
		matrix colname b0=Group_1 Group_c Group_2 Tdifference ToT_Explained ToT_Unexplained
		matrix b=b0,bx,bb
		**now for V0
		matrix v0=[v0,[0,0,0,0]'] \  ///
		           [[0,0,0,0],vx["overall:difference","overall:difference"]]
		matrix v0=[v0,[0,0,0,0,0]'] \  ///
		           [[0,0,0,0,0],vb["overall:difference","overall:difference"]]

		** Flip at some point to make better sense
		local x2=colsof(v0)
		local x1=colsof(vx)
		local cb: colnames b
		local ceqb: coleq  b
		matrix V=[v0,J(`x2',`x1'*2,0)]  \ ///
				[J(`x1',`x2',0),vx,J(`x1',`x1',0)]\  ///
				[ J(`x1',`x1'+`x2',0),vb]
		matrix colname V=`cb'
		matrix coleq V=`ceqb'
		matrix rowname V=`cb'
		matrix roweq V=`ceqb'		
		** returing results
	restore	

	*************************************************************
	}
    *display "is it not doing this"
	ereturn post b V, esample(`touse') depname(`y')
	eret loc title "Blinder-Oaxaca RIF-decomposition"
	eret loc model "Blinder-Oaxaca RIF-decomposition"
    eret loc cmd    "oaxaca_rif"
	eret loc cmdline     "oaxaca_rif `0'"
    eret loc depvar  "`y'"
	eret loc by  "`by'"
	eret loc rifvarp "`rif'"
	eret loc dtype   "`type'"
	eret loc weights "`erweight'"
	eret loc g1 `g1'
	eret loc g2 `g2'
	eret loc gc `gc'
	eret loc N1 `N1'
	eret loc N2 `N2'
	eret loc NC `NC'	
	if "`e(dtype)'"=="Reweighted" {
	   if "`logit'"!="" {
		  eret loc rwmodel "logit"
		  ereturn matrix b_logit=b_rw
		  ereturn matrix V_logit=v_rw
		}
	   else {
		  eret loc rwmodel "probit"
		  ereturn matrix b_probit=b_rw
		  ereturn matrix V_probit=v_rw
		}
	}
	capture matrix drop v0 vb vx b0 bb bx vc bc xs bs xcx bcx xc xm bm
	ereturn local lgd `lgd'
	display_ob
end

capture program drop display_ob
program display_ob
if "`e(cmd)'"!="oaxaca_rif" {
	display "Previous results for oaxaca_rif not found"
	exit
   }
    di as txt "Model  : " as res e(model)
	di as txt "Type   : " as res e(dtype)
	di as txt "RIF    : " as res e(rifvarp)
    di as txt "Group 1: `e(by)' = " as res e(g1) ///
       as txt _col(50) "N of obs 1      `space'= " as res %10.0g e(N1)
	di as txt "Group c: `e(gc)' "  ///
       as txt _col(50) "N of obs C      `space'= " as res %10.0g e(NC)
    di as txt "Group 2: `e(by)' = " as res e(g2) ///
       as txt _col(50) "N of obs 2      `space'= " as res %10.0g e(N2)
	   
    di ""
ereturn display
Display_legend
end 

 capture program drop Display_legend

prog Display_legend
    foreach line in `e(lgd)' {
        local i 0
        local piece: piece `++i' 78 of `"`line'"'
        di as txt `"`piece'"'
        while (1) {
            local piece: piece `++i' 76 of `"`line'"'
            if `"`piece'"'=="" continue, break
            di as txt `"  `piece'"'
        }
    }
end