Stata rename a lot of variables from another list - stata

Question

I'm importing a very complex .xls file that often combines multiple cells together in the variable names. After importing it into Stata, only the first cell has a variable name, and the other 3 are blank. Is it possible to write a loop to rename all the variables (which come in sets of 4)?
For instance, the variables go: Russia, B, C, D but I would like them to be named Russia_A, Russia_B, Russia_C, Russia_D. Is there a way to do this with a loop or command within Stata?

Answer 1

It's impossible to have blank variable names in Stata, as your own example attests. On the information given your variable names come in fours, so that you could loop. One basic technique is just to cycle over 1, 2, 3, 4 and act accordingly. This example works. If it's not what you want, a minimal reproducible example is essential showing why this is different from what you want.
clear
input Russia B C D Germany E F G France H I J
42 42 42 42 42 42 42 42 42 42 42 42
end
tokenize "A B C D"
local i = 0
foreach v of var * {
local ++i
if `i' == 1 local stub "`v'"
rename `v' `stub'_``i''
if `i' == 4 local i = 0
}
ds
Russia_A Russia_C Germany_A Germany_C France_A France_C
Russia_B Russia_D Germany_B Germany_D France_B France_D
tokenize is possibly the least familiar command here, so see its help if needed.
All that said, it's unlikely that this is a useful data structure. See help reshape.
Here's another way to do it. We set up a counter running over all the variables. This perhaps is more of a finger exercise in macro manipulation.
clear
input Russia B C D Germany E F G France H I J
42 42 42 42 42 42 42 42 42 42 42 42
end
tokenize "A B C D"
forval j = 1/4 {
local sub`j' "``j''"
}
unab all : *
tokenize "`all'"
local J : word count `all'
forval j = 1/`J' {
local k = mod(`j', 4)
if `k' == 0 local k = 4
if `k' == 1 local stub "``j''"
rename ``j'' `stub'`sub`k''
}
ds