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Re: st: AW: Create a flag variable for 10 most frequent values
Ugh. How silly of me.
I think this does it, though it doesn't deal with values that are tied
for 10th:
sysuse auto
bysort mpg: gen n=_N
bysort n mpg: gen top10=(_n==1)
replace top10 = sum(top10)
sum top10, meanonly
replace top10 = (top10>=(`r(max)'-9))
To flag the top 10, along with any additional that have the same
frequency as the 10th:
bysort mpg: gen n=_N
bysort n mpg: gen tag=(_n==1)
replace tag = sum(tag)
sum tag , meanonly
gen top10ties = (tag>=(`r(max)'-9))
sum n if tag==(`r(max)'-9), meanonly
replace top10ties = 1 if n==`r(max)'
table mpg top10
table mpg top10ties
On 11/16/2009 7:10 PM, Martin Weiss wrote:
<>
Why is "18", which is the most frequent "mpg" value, assigned a "0" for
"top10" in your example? Your code seems to flag the highest values (my
initial mistake), and not the most frequent ones...
HTH
Martin
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Nick Winter
Sent: Dienstag, 17. November 2009 00:57
To: [email protected]
Subject: Re: st: AW: Create a flag variable for 10 most frequent values
No collapsing, no merging, no -egen-:
sysuse auto
bysort mpg: gen top10=(_n==1)
replace top10 = sum(top10)
sum top10, meanonly
replace top10 = (top10>=(`r(max)'-9))
On 11/16/2009 6:37 PM, Martin Weiss wrote:
<>
Good point! I always make up my own dataset according to the description
in
the initial post, and in this case, my dataset may have been too simple.
Still, Elan can -merge- back with the original dataset, with "diagnosis"
as
her key.
***
sysuse auto, clear
keep mpg
bys mpg: egen mycount=count(mpg)
//collapse to one per group
bys mpg: keep if _n==1
//-sort- on count var
sort mycount
//take the last ten
gen byte mostfreq=inrange(_n,`=_N-9',_N)
//and back as we were
expand mycount
merge m:m mpg /*
*/ using "C:\Program Files (x86)\Stata11\auto.dta", /*
*/ nogenerate nolabel nonotes
***
You need to substitute the path to your auto dataset in the last line...
HTH
Martin
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Sergiy Radyakin
Sent: Dienstag, 17. November 2009 00:03
To: [email protected]
Subject: Re: st: AW: Create a flag variable for 10 most frequent values
suppose you have data with two vars: name and diagnosis (or make and mpg)
and you want to add "top10" dummy to that.
You keep one person for each diagnosis
After you -expand- there will be N persons with the same name?
Can you show this with auto.dta?
S.R.
On Mon, Nov 16, 2009 at 5:36 PM, Martin Weiss <[email protected]>
wrote:
<>
What do you want to know? I collapse (fineprint: no hyphens around it as
I
use -keep- to do it) the thing to be able to -sort- on "mycount" and
assign
the flag that Elan requested. Once that is done, I want my original data
back, so I -expand- it back to its former glory. Any suggestions for
improvements are welcome...
HTH
Martin
-----Ursprüngliche Nachricht-----
Von: [email protected]
[mailto:[email protected]] Im Auftrag von Sergiy
Radyakin
Gesendet: Montag, 16. November 2009 23:33
An: [email protected]
Betreff: Re: st: AW: Create a flag variable for 10 most frequent values
Martin, could you please explain how -expand- is used here?
Best, Sergiy
On Mon, Nov 16, 2009 at 5:14 PM, Martin Weiss <[email protected]>
wrote:
<>
Here is a strategy:
*************
clear*
//construct data
set obs 10000
gen dx=1+int(100*runiform())
//see freqs
ta dx
//use ben jann`s -fre-
capture which fre
if _rc ssc install fre
fre dx, desc
//get counts next to "dx"s
bys dx: egen mycount=count(dx)
//collapse to one per group
bys dx: keep if _n==1
//-sort- on count var
sort mycount
//take the last ten
gen byte mostfreq=inrange(_n,`=_N-9',_N)
//and back as we were
expand mycount
//see result
ta myc mostfreq
*************
HTH
Martin
-----Ursprüngliche Nachricht-----
Von: [email protected]
[mailto:[email protected]] Im Auftrag von Cohen, Elan
Gesendet: Montag, 16. November 2009 22:25
An: '[email protected]'
Betreff: st: Create a flag variable for 10 most frequent values
Hi all,
I have a string variable dx that represents a patient's diagnosis (about
5,000 unique values). I'd like to create a "top 10 flag" that equals 1
if
dx is one of the top 10 most frequent diagnoses and 0 otherwise.
I'm not even sure where to begin. If someone could point me in the
right
direction, I'd be grateful. Stata 10, Windows XP
Thank you,
- Elan
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--
--------------------------------------------------------------
Nicholas Winter 434.924.6994 t
Assistant Professor 434.924.3359 f
Department of Politics [email protected] e
University of Virginia faculty.virginia.edu/nwinter w
PO Box 400787, 100 Cabell Hall
Charlottesville, VA 22904
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