Re: st: Pulling in files and data stored in a folder tree

["Lacy,Michael" <Michael.Lacy@colostate.edu>]

"Ben Hoen" <bhoen@lbl.gov> wrote:

>Date: Fri, 27 Jul 2012 11:26:31 -0400
>Subject: st: Pulling in files and data stored in a folder tree
>
>Hi Statalisters,
>
>I have a set of ~ 200,000 records stored in one dataset (“master file”) each
>of which has a year and a county to which it applies, and a unique record
>id.  Separately I have a large set of files that are stored by county (of
>which there are 20, so there are 20 county folders) and year (for each
>county there are 10 year folders – 2002 through 2011).  In each year folder,
>there are 4 files that I want to pull data from (via 1:1 merge with the
>“master file” using the record id).  There are roughly 10 variables I want
>to add to the master file from these 4 files, or approximately 2 to 3 from
>each file.
>
>So, the question is how I might write code that will go through each record
>in the master file, determine the year and the county, go through the folder
>tree to find the appropriate year in the appropriate county, and then merge
>with the four files “keeping” the data from the 10 variables?
>
>A few things to note:  1) the files I want to pull data from are column
>separated text files (i.e., I have not gone through the trouble of
>converting then to Stata files yet – but could…); and, 2) all of the files
>from which I want to pull data are named by county and year (e.g.,
><countyname>_<year>_<filename>) and these names match exactly with the
>county names and years stored in the master file. 
>

Yes, you need to convert them first to Stata files.
I'd think about applying -levelsof- to your master file to get 
the names of each of your county/year combination,  and use 
that to get into folder containing each  that you need
to -insheet- into a Stata file.  I'd put each of these into
a numbered list of tempfiles, and then merge each
one onto your master.

Something like this is what I was thinking of :

use master
levelsof county,local(counties)
levelsof year, local(years)
clear
cd "directory holding all the county-year files"
local basedirectory = "whatever"
local filecount = 0
// Put all the using files into Stata format,
// and save them in numbered temp files
foreach c of local counties {
   foreach y of local years {
     cd "`basedirectory\`c'\`y'"  // whatever fits your file system
     insheet using "first file of 4" .....
     local filecount = `filecount' + 1
     keep ...list of the variables of interest from file 1
     tempfile temp`filecount'
     save `temp`filecount''
     ....
     ....
     local filecount = `filecount' + 1
     insheet using "last file of 4" .....
     local filecount = `filecount' + 1
     keep ...list of the variables of interest from file 4
     tempfile temp`filecount'
     save `temp`filecount''
   }
}     
//
forval i = 1/`filecount' {
   merge 1:1 county year using "`temp`i''"
   tab1 _merge
   keep if (_merge != 2) 
	drop _merge		         
}
     

Regards,

Mike Lacy
Dept. of Sociology
Colorado State Universty
Fort Collins CO  U.S






Mike Lacy
Assoc. Prof./Dir. Grad. Studies
Dept. of Sociology
Colorado State University
Fort Collins CO 80523-1784
970.491.6721 (voice)

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