st:looping over 41 months over 3 full years(12 months each) and a half year (5 months)

[Amanda Fu <mandy.fu1@gmail.com>]

Dear Statalisters,

I encounter a question related to looping. I have 41 variables that
indicating each month from Jan 2000 to May 2003.I would like to rename
the variables  into some format as var_`m'_'y'. M means month, y means
year. It looks like the following:
-------------------------------------------------------------
date            var name       new name
Jan2000        var1        var01_2000
Feb2000       var2        var02_2000
.....
Dec2000     var12        var12_2000
Jan2001      var13        var01_2001
Feb2001      var14        var02_2001
.....
Dec2001     var24         var12_2001
................
Jan2003      var37         var01_2003
.......
May2003     var41         var05_2003
--------------------------------------------------------------

QUESTION 1: var01_2000  vs. var1_2000

I find it is not easy to add the 0 before those months earlier than
10. The reason I wanted to rename it as 01,02 ... is that without the
0 sometimes the sequence of the variables will be messy , like:
1,11,12,2,3,.... Alternatively I can just rename as var1_2000,.... and
then adjust the order of the variables.

May I know how will you choose between var01_2000 and var1_2000?

QUESTION 2:  the 5 months in 2003 separately or not

The following is the code I write to rename the variables (using
var1_2000, without 0 before month 1). I separated 2003 from the
previous years since in 2003 there are only 5 month, since I have not
figure out how to put 2003 together with the rest years.

I think there could be some easy way to deal with this. Would anyone
give me some suggestion on how to simplify the codes?

***** rename as "var1_2000","var2_2000"  no 0 before month
********************2000-2002 first
local j=0
pro define renamevar
local ++j
foreach y of 2000(1)2002 {
foreach m of 1/12 {
rename var`j'       var`m'_`y'
}
}
****************** 2003 second
local j2=36
foreach m of 1/5 {
local ++j2
rename var`j2'       var`m2'_2003
}
end
renamevar
*************************************************************

Thank you for your time! I appreciate it!

Best regards,
Amanda
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