CODEWITHSUNDEEP
stata
RayofCommand
RayofCommand

Reputation: 4244

How to delete variables which occur in column x but not in column y?

How can I delete duplicates which occur in column x but not in column y?

My dataset is as follows:

+-------+---+---+
| year  | x | y |
+-------+---+---+
|  2001 | 1 | 2 |
|  2001 | 2 | 3 |
|  2001 | 2 | 3 |
|  2001 | 4 | 6 |
|  2001 | 5 | 9 |
|  2001 | 4 | 2 |
|  2001 | 4 | 9 |
+-------+---+---+

What I want is to remove the entries which occur in column y from the ones in column x. My result would be: 1,4,5

I am currently learning Stata and I would love to know a good source for all possible commands, if this exists? So I can learn better on my own. Currently I have trouble to find good sources.

Upvotes: 0

Views: 368

Answers (1)

Nick Cox
Nick Cox

Reputation: 37208

In Stata what you call columns are always called variables.

See http://www.statalist.org/forums/help#stata for general advice on how to present data examples in Stata questions. (The comments on CODE delimiters don't apply here.)

This may help. I didn't understand the role of year in your problem. 

clear 
input year   x  y 
  2001  1  2 
  2001  2  3 
  2001  2  3 
  2001  4  6 
  2001  5  9 
  2001  4  2 
  2001  4  9 
end 
rename x Datax 
rename y Datay 
gen long obs = _n 
reshape long Data, i(obs) j(which) string 
bysort Data (which) : drop if which[_N] == "y" 
list 

     +---------------------------+
     | obs   which   year   Data |
     |---------------------------|
  1. |   1       x   2001      1 |
  2. |   4       x   2001      4 |
  3. |   7       x   2001      4 |
  4. |   6       x   2001      4 |
  5. |   5       x   2001      5 |
     +---------------------------+

All possible commands aren't documented in a single place. Someone could write new commands all the time and they would not be documented anywhere except their help files. Did you mean that? Nor are all existing commands documented in one place: many are user-written and most of those are just documented by their help files.

Most of the official commands in Stata as supplied by StataCorp are documented in the manuals. Literally, there are also undocumented commands (I am not inventing this: see help undocumented) and there are also nondocumented commands that exist, known about because StataCorp mention them in talks or emails. To be as positive as possible: start with the manuals, bundled with your copy of Stata as .pdf files.

Upvotes: 1

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