st: Loop: matching variables (in order)

[Nick Bornschein <nick.bornschein@gmail.com>]

Hello,

I have written the following loop, but there is a mistake when
creating the graphs I cannot solve.
First of all, I have an ordered list of x variables and an ordered
list of y variables. I want to create an graph (tsline) with 2 lines,
where I want use the first variable of the x variables and the first
variable of the y variables, then I want to create the next graph with
2 lines with the second variable of the x variables and the second
variable of the y variables. How can I write that into the loop?


foreach x of varlist apple-biorad {
    foreach y of varlist apple_m30-biorad_m30 {
      tsline `x' if datum >= `=date("01jan2010", "DMY")' || tsline `y'
if datum >= `=date("01jan2010", "DMY")'
      graph export Grafiken/`x'_m30.png, replace
    }
}
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