Combination of variables

[Enrique Alameda]

Dear all,

I have three variables m1, m2 and m3 equal to 11 71 999 respectively. I would like to create a new variable, m4, equal to the "combination" of the three. In essence, m4 = 1171999. I need to do this for thousands of occurrences and have not been able to generate a suitable code for this. Does anyone know how to do this? I am new to Stata so apologies if this is a simple question.

Thank you in advance

All the best,

Enrique

[Thomas Brot]

Hello Enrique.

Are your variables m1, m2 and m3 string, or numeric ? If they are string, you can do this with the data I provided :

* Example generated by -dataex-. For more info, type help dataex
clear
input str3(m1 m2 m3)
"11" "71" "999"
end

gen m4 = m1 + m2 + m3

di m4

For string variables, the operator "+" actually means "concatenate". If your variables are numeric, you'll have to turn them into string variables first. To do so, look at

help tostring

I hope that helped

[Enrique Alameda]

Hi Thomas, thank you very much. This is exactly what I wanted. All the best

[Nick Cox]

#2 is not quite right, as egen, concat() will concatenate numeric values without using tostring at all. But it does indeed convert to string within the code.

clear
input m1 m2 m3
11 71 999
end

egen m4 = concat(m?)

list 

     +-------------------------+
     | m1   m2    m3        m4 |
     |-------------------------|
  1. | 11   71   999   1171999 |
     +-------------------------+