topic Re: How to copy only selected variables from a Null dataset to another dataset? in SAS Programming

How to copy only selected variables from a Null dataset to another dataset?

john83 — Sat, 07 Jan 2012 20:56:52 GMT

Hi Guys,

I have a null dataset with 20 variables. i want to copy the variables which contain name like a or k in another dataset.how can we create the dataset?

Thank you,

John

Re: How to copy only selected variables from a Null dataset to another dataset?

art297 — Sat, 07 Jan 2012 21:04:06 GMT

One method although I'm sure there are many others:

proc sql;

create table want

like sashelp.class (keep=n: a:)

;

quit;

How to copy only selected variables from a Null dataset to another dataset?

john83 — Sat, 07 Jan 2012 21:21:18 GMT

Sir, Your reply helped me find a solution.But, it is correct only when the source dataset is a normal dataset.

Following is the code:

data meng;

set sashelp.class(keep=n: a:);

run;

proc print data=meng;

run;

I am looking for a solution when Source dataset is a null dataset.

Thank you,

John

Re: How to copy only selected variables from a Null dataset to another dataset?

art297 — Sat, 07 Jan 2012 22:01:03 GMT

The method I proposed works with null datasets. e.g., try the following combination:

proc sql;

create table class

like sashelp.class

;

quit;

proc sql;

create table want

like class (keep=n: a:)

;

quit;

Or am I misunderstanding what you are asking?

Re: How to copy only selected variables from a Null dataset to another dataset?

Patrick — Sun, 08 Jan 2012 01:32:42 GMT

I believe there is some confusion around the term "null dataset".

Art seems to define it as "a dataset without rows" where John seems to talk about a "data _null_;" step.

@John

If above is true then please be aware that "data _null_;" means no dataset at all gets created so there can't be such a thing like a "_null_ dataset" as you define it.

You could do something like below to capture only variable definitions whithout writing any rows (=a dataset without any rows):

data Mapping(keep=n: a:);
if 0 then output Mapping;
set sashelp.class;
/* ..... */
run;

proc contents data=Mapping;
quit;

How to copy only selected variables from a Null dataset to another dataset?

john83 — Sun, 08 Jan 2012 07:55:05 GMT

Thanks for the reply @art297 and @Patrick.

How to copy only selected variables from a Null dataset to another dataset?

Ksharp — Mon, 09 Jan 2012 05:43:45 GMT

Like what Patrick has been mentioned. Another way is:

data want;

if 0 then set class(keep=name sex);

stop;

run;

Ksharp

How to copy only selected variables from a Null dataset to another dataset?

Linlin — Mon, 09 Jan 2012 14:26:51 GMT

Hi Kshart,

why you add "stop" in your code?

Thank you!

How to copy only selected variables from a Null dataset to another dataset?

art297 — Mon, 09 Jan 2012 14:30:51 GMT

Linlin, KSharp is in a different time zone, thus I'll provide an answer in his place. Using the method he proposed, there is no need to read the file. Stop exits the program at that point without reading any records.

How to copy only selected variables from a Null dataset to another dataset?

Linlin — Mon, 09 Jan 2012 14:35:59 GMT

Thank you Art!

I thought with "if 0 then set class(keep=name sex)", "stop" is not necessary.

How to copy only selected variables from a Null dataset to another dataset?

art297 — Mon, 09 Jan 2012 14:41:26 GMT

Actually, you are right and I was wrong. Given that syntax SAS will automatically stop the looping, thus the stop statement isn't needed. However, it doesn't hurt to have it and will ensure that the datastep is stopped.

Re: How to copy only selected variables from a Null dataset to another dataset?

Linlin — Tue, 10 Jan 2012 01:08:53 GMT

Hi Art,

Kshart and you are right. to get 0 observation, "stop" is necessary .

data dsn5; /* dsn5 has 0 observation */

if _n_ =0 then set dsn3;

stop;

run;

data dsn6; /* dsn6 has 1 observation with missing value for the variables */

if _n_ =0 then set dsn3;

run;

Thank you!

Linlin