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Re: -merge- (?) problem (was: st: MIME-Version: 1.0)


From   "Eva Poen" <eva.poen@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: -merge- (?) problem (was: st: MIME-Version: 1.0)
Date   Mon, 29 Sep 2008 16:33:51 +0100

Ashim,

Please try and use Stata lingo in your postings: observations (not
rows, or items) and variables (not columns).

You can do it much easier. -help merge- will provide some good information.

***
use secondfile
sort symbol year
save, replace

use firstfile
sort symbol
merge symbol using secondfile, uniqmaster
save mergefile
***

Now you will have ticker as a variable in you second file. Inspect the
_merge variable (see -help merge-) to make sure the outcome is what
you expected.

Next:
***
qui levelsof symbol, local(loop)
foreach x of local loop {
drop _all
use mergefile
keep if symbol == "`x'"
save `=ticker[1]'
}
***

HTH,
Eva

2008/9/29 Ashim Kapoor <ashimkapoor@gmail.com>:
> Hello Eva,
>
> Thank you for your time. Let me be more clear this time.
>
> In the first file I have 2 variables--> symbol and ticker. The tickers
> are file names I want to save various output files as.  There is a one
> one correspondence between symbol and tickers. For example.
>
>     symbol    ticker
> 1.    ABB       abb
> 2.    BHARTI  bti
> 3.    AIRTEL   artl
>
>
> That is what the first file looks like.
>
> the second file has variables year / symbol / production / etc.
>
> It looks like
>
>   symbol              year    production
> 1.   ABB              1998          92
> 2.   ABB              1999          95
> 3.   BHARTI          1998          61
> 4.   BHARTI           1999         70
> 5.   AIRTEL           2000          80
> 6.  AIRTEL            2001          81
>
> Now I want to save items 1 and 2. ie. items with symbol = ABB in a
> file named "abb.dta"
> I want to saves items 3 & 4 ie. items with symbol= BHARTI in a file
> named "bti.dta"
> and items with symbol = "AIRTEL" in a file named "artl.dta".
>
> So I guess this would be a 2 step procedure.
>
> Step 1 : store all symbols in ONE local macro and store all tickers in
> the 2nd local macro.
>
> Step 2 : Loop through the 2 equal sized loops, do a keep if symbol ==
> ...... and save as the corresponding ticker .
>
> Can u tell me how to do this in stata ?
>
> Thank you,
> Ashim.
>
> On Mon, Sep 29, 2008 at 4:38 PM, Eva Poen <eva.poen@gmail.com> wrote:
>> Ashim,
>>
>> I'm sorry but I don't get it. You have two variables in your first
>> file, called symbol and ticker. What are they? Numeric, string? In
>> your second file you have symbol again (what about ticker?), and many
>> more variables, and you also have more observations (symbol does no
>> longer uniquely identify observations).
>>
>> Now you want to do some operation that looks suspciously like a
>> -merge-, but it's unclear to me. For each symbol from file 1, you want
>> to -use- file 2 and -keep- all observations with this symbol.
>> Following what you said earlier, you will now be left with approx. 100
>> observations and many variables. Now you say you want to save this "as
>> ticker in the 1st file". What do you mean by that? You want to save
>> all 100 observations and many variables, in the first file? And what's
>> that to do with ticker? Ticker already exists in the first file. Do
>> you want to replace it, and with what information? Or do you want to
>> add ticker to the second file?
>>
>> You'll have to be more precise for someone to be able to help.
>>
>> Eva
>>
>> 2008/9/29 Ashim Kapoor <ashimkapoor@gmail.com>:
>>> Hello everyone,
>>>
>>> I have 2 files.
>>>
>>> The 1st file has 2 columns --> symbol and ticker. [ each symbol is
>>> only in one observation ]
>>>
>>> The 2nd file has many more columns --> symbol and many other vars. [
>>> each symbol is in around 100 observations here ]
>>>
>>> I want to say foreach symbol in 1st file  {
>>>
>>> use 2nd file
>>>
>>> keep if symbol ==above symbol
>>>
>>> save as ticker in the 1st file
>>>
>>> }
>>>
>>>
>>> Can someone tell me how to do this ?
>>>
>>> I guess to start with I would have to save the entire observations in
>>> symbol var in 1st file in ONE local macro and similarly for the
>>> ticker. Can someone tell me how to do this ?
>>>
>>> Thank you,
>>>
>>> Ashim.
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