st: A “loop” to merge dataset with a different file each time?

[Kremlin Wickramasinghe <kremlin.wickramasinghe@dph.ox.ac.uk>]

Dear all, 
  I want to merge two datasets and run an analysis 1000 times in a loop. I want to write a do file to automate this analysis. 
 
My master dataset has nutrition information of different foods (with a unique food code for each food name). I want to merge it with another dataset which contain food price data for those food codes. I have food prices from 1000 different stores in 1000 different Excel sheets. I have saved them with filenames with a sequence from 1-1000. (foodpricedata_1 to foodpricedata_1000) .   I want to  write a do file to automate the process of 
a)      Do m:1 merge using foodcode , but each time use a different food price data file. 
b)      Run the analysis 
 
The following do file shows the steps of running this analysis twice, first time  with the foodpricedata_1 and second time with the foodpricedata_2 files. I want to automate this to run 1000 times but each time using a unique file. I have seen tutorial on how to run a loop, but couldn’t find any resources on how to make it a loop using a different file in each time .  I would be most grateful if someone could guide me on how to do this. 
 
Do File : 
 
insheet using "C:\ DATA\uncertainty analysis\for meging.txt", clear 
sort foodcode 
save "C:\DATA\uncertianity analysis\master.dta", replace 
 
insheet using "C:\DATA\uncertianity analysis\foodpricedata_1.txt" , clear 
save "C:\DATA\uncertianity analysis\working.dta", replace 
sort foodcode
merge m:1 foodcode using "C:\DATA\uncertianity analysis\master.dta",
 
*** Analysis***
generate totalghgeR = real( totalpricekg)
gen Tghgecode =  totalghgeR *  numberofportions
total  Tghgecode
 
 
clear 
 
insheet using "C:\DATA\uncertianity analysis\for meging.txt", clear 
sort foodcode 
save "C:\DATA\uncertianity analysis\master.dta", replace 
 
insheet using "C:\DATA\uncertianity analysis\ foodpricedata_2.txt" , clear 
save "C:\DATA\uncertianity analysis\working.dta", replace 
sort foodcode
merge m:1 foodcode using "C:\DATA\uncertianity analysis\master.dta",
 
*** Analysis***
generate totalghgeR = real( totalpricekg)
gen Tghgecode =  totalghgeR *  numberofportions
total  Tghgecode
 
 
clear

End of Do file …..

Best wishes
Kremlin 

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