Deleting variables with specific values in a specific row

[Ellim Jung]

I would like to keep variables if the third-row value is SHD.
If the third-row value is not SHD, I would like to delete all the variables.

I do not want to use the 'xpose 'command because the data is very long, so it is not workable.
In my dataset, there are more than 2000 variables including more than 100 SHD and more than 30000 observation.
I tried the below code but failed.
I would like to use logic similar to the below.
PLZ let me know good ways.



foreach var of varlist * {
drop `var' if `var'[3] == "SHD"
}

V119	V534	V1461	V1942	V1943	V2165	V2542	V2543	V2791	V3002	V3046
1968	1968	1968	1968	1968	1968	1968	1968	1968	1968	1968
1	2	3	4	5	6	7	8	9	10	11
SEX	FMN	SHD	AGE	SEX	SHD	AGE	SEX	SHD	1973	MI_Y
1	1
		1	49	2	5	50	2	5	81	5179
	1	5	24	1	5	25	1	5	17	8000
1	2
		1	59	2	5	60	2	5	2285	0
1	3	5	82	1	5
1	4	5	48	1	5	49	1	5	430	0
						20	1	1	432	5200

[William Lisowski]

Added in edit:

I see the problem now. Try

foreach var of varlist * {
if `var'[3] == "SHD" drop `var'
}

The output of help drop gives a hint - drop does not take the if qualifier when dropping variables. You need the programmer's if command described in help ifcmd.

The advice on what constitutes a helpful post given in my original post below remains good advice.

Original post:

The code you show appears correct, so your problem really isn't clear without more detail, or at a minimum it is too difficult to guess at a good answer from what you have shared. Please help us help you. Show your code and what Stata told you by copying the commands and the resulting error message from Stata's Results window and pasting it into a post using code delimiters [CODE] and [/CODE].

The Statalist FAQ provides advice on effectively posing your questions, posting data, and sharing Stata output. Section 12.1 is particularly pertinent

12.1 What to say about your commands and your problem

Say exactly what you typed and exactly what Stata typed (or did) in response. N.B. exactly!
...
Never say just that something "doesn't work" or "didn't work", but explain precisely in what sense you didn't get what you wanted.