compare contents two variable

[ANA KHAILFI]

I was wondering if you know of any command in stata that can compare modalities of two columns(2 string variable.)
iw would like to complete for exemple var1 withi different modalities of var2
For example :

var1 var2
A C
AB D
D AE
. AB

HERE, i would like to comple the missing value of var1 with AE because AE is in var2 and not in var1
i used lovelsof but they are problem!!
levelsof var1, local(levels)
levelsof var2, local(level)
gen index = 1 if strpos(var2,"`levels'")

[Carlo Lazzaro]

Ana:
you may want to try:

. egen flag=diff( var1 var2 )///to check whether observations in -var1- and -var2- are equal or not. In this latter case -flag- will take on 1 (0 otherwise)

. replace var1="AE" if var1==""///to replace missing values as desired
(1 real change made)

[ANA KHAILFI]

Thank you Carlo
But AE is an exemple
This résult of collapse fonction
So, il want replace missing value of var 1 with the other modalities of var2.

[Carlo Lazzaro]

Ana:
try:

replace var1=var2 if var1==""

[ANA KHAILFI]

Thank you
But Carlo il thank il must use levelsof. .
If modalities of var 2 not in var 1
Il add this modalities tout var 1

[Carlo Lazzaro]

Ana:
sorry, but I cannot follow your query, then.

[ANA KHAILFI]

Thank you carlo

[William Lisowski]

This discussion is continued at

opposite of strpos