Stata FAQ
How do I assign the values of one variable as the value labels for another variable?

Sometimes two variables in a dataset may convey the same information, except one is a numeric variable and the other one is a string variable.  For example,  in the data set below, we have a numeric variable a coded 1/0 for gender and a string variable b also for gender but with more explicit information.  It is easy to use the numeric variable, but we may also want to keep the information given from the string variable.  This is a case where we want to create value labels for the numeric variable based on the string variable. In Stata, we can use the command called labmask to create value labels for the numeric variable based on the character variable.  The command labmask is one of the commands in a suite called labutil written by Nicholas J. Cox.  You can download it by typing findit labutil (see How can I use the findit command to search for programs and get additional help? for more information about using findit) and then following the link to it. 

Example 1: A simple example

clear

input gender str8 female
1 female
0 male
end
list

     +-----------------+
     | gender   female |
     |-----------------|
  1. |      1   female |
  2. |      0     male |
     +-----------------+

labmask gender, values(female)

describe

Contains data
  obs:             2                          
 vars:             2                          
 size:            32 (99.9% of memory free)
-------------------------------------------------------------------------------
              storage  display     value
variable name   type   format      label      variable label
-------------------------------------------------------------------------------
gender          float  %9.0g       gender     
female          str8   %9s                    
-------------------------------------------------------------------------------
Sorted by:  
     Note:  dataset has changed since last saved

list

     +-----------------+
     | gender   female |
     |-----------------|
  1. | female   female |
  2. |   male     male |
     +-----------------+

label list
gender:
           0 male
           1 female

Example 2: Another example

How is labmask different from encode?  Both of the commands create value labels for the numeric version of the string variable.  However, the command encode does it based on the alphabetical order of the string values, not based on the values of the numeric variable in the data set that we want to match it to.  For example, the new variable cnum below created by encode will have value 1 for boston since it the first alphabetically.

clear
input cityn  str8 cityc
 0       la
 0       la
 2       boston
 2       boston
 5       chicago
 5       chicago
 5       chicago
 3       ny
 3       ny
end

encode cityc, gen(cnum)

labmask cityn, values(cityc)

list

     +-----------------------------+
     |   cityn     cityc      cnum |
     |-----------------------------|
  1. |      la        la        la |
  2. |      la        la        la |
  3. |  boston    boston    boston |
  4. |  boston    boston    boston |
  5. | chicago   chicago   chicago |
     |-----------------------------|
  6. | chicago   chicago   chicago |
  7. | chicago   chicago   chicago |
  8. |      ny        ny        ny |
  9. |      ny        ny        ny |
     +-----------------------------+

list, nolab

     +------------------------+
     | cityn     cityc   cnum |
     |------------------------|
  1. |     0        la      3 |
  2. |     0        la      3 |
  3. |     2    boston      1 |
  4. |     2    boston      1 |
  5. |     5   chicago      2 |
     |------------------------|
  6. |     5   chicago      2 |
  7. |     5   chicago      2 |
  8. |     3        ny      4 |
  9. |     3        ny      4 |
     +------------------------+