How to assign row number in a dataset to a new variable

[kanishk gaggar]

SHROUT	RETX	sprtrn	event_date	event_window
2516605	0.00555951	0.00027547	-10	.
2516605	-0.0051057	0.00528225	-9	.
2516605	0.01555526	0.00035666	-8	.
2516605	-0.0028723	0.00373984	-7	.
2516605	-0.0001436	0.00189784	-6	.
2516605	-0.0067038	-0.0022133	-3	.
2516605	-0.0148939	-0.0036523	-2	.
2516605	-0.0032213	-0.0028032	-1	.
2516605	0.00224598	-0.0016543	0	0
2516605	-0.0030787	0.00013443	4	.
2516605	-0.0147525	-0.0044303	5	.
2516605	0.00207242	0.00570143	6	.
2516605	-0.0001382	0.00026927	7	.
2516605	0.02433849	0.00767039	8	.

Hi,

I have the above dataset. I am trying to generate a variable which returns the row number where variable event_window == 0

I need to retain a 3-day or a 5-day window around the event.

Please advise.

Thanks and regards,
Kanishk

[Andrew Musau]

I need to retain a 3-day or a 5-day window around the event

I do not understand this condition, but the observation number in Stata is indicated by "_n". So your command will be something like

gen wanted= _n if event_window == 0

Note that the observation number depends on the sort order, so you may want sort your observations specifying some criterion using bysort, otherwise these values will be arbitrary.

[Nick Cox]

My guess is that whatever you want to do doesn't need a "row number" at all, as all the information required is already captured by existing variables.


For example, this code gives a mean for a 3-day window centred on the event

egen wanted  = mean(RETX) if inrange(event_date, -1, 1), by(SHROUT)

and this code spreads that result to the entire panel:

egen wanted  = mean(cond(inrange(event_date, -1, 1), RETX, ,), by(SHROUT)

More at https://www.stata-journal.com/articl...article=dm0055

[Nick Cox]

There is a parenthesis missing in #3. And another typo. Sorry to anyone puzzled by either.

 
 egen wanted  = mean(cond(inrange(event_date, -1, 1), RETX, .)), by(SHROUT)