topic Re: help me to understand _file_ in SAS Programming

help me to understand _file_

Linlin — Mon, 09 Apr 2012 15:22:29 GMT

When I run the code below, macro variable &rename=

ABC=ID F1=Name F2=Sex FDG=Country ABC=id1 F1=name1 F2=sex1 FDG=country1

I expect &rename= ABC=id1 F1=name1 F2=sex1 FDG=country1

I don't understand Why _file_ has the values of two observations instead of just second observation?

Thanks - Linlin

data have;

input (ABC F1 F2 FDG)($);

cards;

ID Name Sex Country

id1 name1 sex1 country1

1 ABC M IND

2 BCD F USA

3 CDE M GER

4 DGE M UK

;

%let rename=;

filename nosee dummy;

data _null_;

file nosee;

set have (obs=2);

put (_all_) (=) @;

call symputx('rename',_file_);

run;

%put &rename;

Re: help me to understand _file_

art297 — Mon, 09 Apr 2012 15:41:28 GMT

Linlin: take a look at: http://support.sas.com/rnd/base/datastep/dsv7-sugi.pdf

Your put statement ends with an @ symbol, thus the buffer will not be cleared at the end of the iteration.

Re: help me to understand _file_

Peter_C — Mon, 09 Apr 2012 16:02:11 GMT

Linlin

I think you misunderstand OBS=

Did you intend to use only the second obs?

Then add data set option FIRSTOBS=2 as well as OBS=2

Art,

if that @ is removed, the _file_ buffer will be empty at the call symputx() statement.

(of course, a "clearing" PUT; statement with no @ could be added after the symputx(), but I think the issue is about the SET )

Re: help me to understand _file_

Linlin — Mon, 09 Apr 2012 16:48:37 GMT

Thank you Art! I will read the paper. - Linlin

Re: help me to understand _file_

MikeZdeb — Mon, 09 Apr 2012 16:54:30 GMT

hi ... you are better off looking at Peter's answer in that you need that @ sign to keep the results in the buffer

the problem is (as Peter stated) the meaning of OBS ... you asked for two observations, not 1

Re: help me to understand _file_

Linlin — Mon, 09 Apr 2012 16:57:43 GMT

Hi Peter,

Thank you for your reply! I know how OBS works. What I don't undestand is why _file_ retains the values of first observation.

Linlin

Re: help me to understand _file_

Peter_C — Mon, 09 Apr 2012 17:05:13 GMT

Linlin

(Since you understand what OBS= is for, I don't understand why you didn't also use FIRSTOBS=

as the macro variable will hold only the results from the final iteration of the data step)

Has Art's response clarified why the final iteration of your data step puts both sets of observations into &RENAME? (focus on that @ )

Peter

Re: help me to understand _file_

MikeZdeb — Mon, 09 Apr 2012 17:12:15 GMT

hi (again) ... if you look near the end of the discussion at ...

https://communities.sas.com/message/107661#107661

there's another example that uses _FILE_ and you'll see that there's a second PUT statement that clears the results of the previous PUT statement that ended with the @ sign

Re: help me to understand _file_

Linlin — Mon, 09 Apr 2012 17:21:35 GMT

Thank you Mike and Peter! I need to read more papers to help me to understand how _file_, _infile_ work. - Linlin

Re: help me to understand _file_

Linlin — Mon, 09 Apr 2012 20:12:05 GMT

Thank you for your input. I am not sure I understand put with a trailing@, put without a trailing@, _file_, _infile_ 100%, but at least I know how to use them (I consider my time well spent).

To use the second observation as variable names in my example, I need to add another put statement to my original code as Mike pointed out.

data have;

input (ABC F1 F2 FDG)($);

cards;

ID Name Sex Country

id1 name1 sex1 country1

1 ABC M IND

2 BCD F USA

3 CDE M GER

4 DGE M UK

;

%let rename=;

filename nosee dummy;

data _null_;

file nosee;

set have (obs=2);

put (_all_) (=)@ ;

call symputx('rename',_file_);

put;

run;

%put &rename;

Of course the code below also works.

filename nosee dummy;

data _null_;

file nosee;

set have (firstobs=2 obs=2);

put (_all_) (=)@ ;

call symputx('rename',_file_);

run;

%put &rename;

Linlin

Re: help me to understand _file_

MikeZdeb — Mon, 09 Apr 2012 22:01:30 GMT

hi ... more reading material about _INFILE_ ...

Now _INFILE_ is an Automatic Variable − So What?

Howard Schreier

http://www.nesug.org/proceedings/nesug01/cc/cc4018bw.pdf

More _Infile_ Magic

Peter Crawford

http://www2.sas.com/proceedings/sugi28/086-28.pdf

I haven't seen any equivalent papers on _FILE_, only postings on SAS-L and here on COMMUNITIES

Re: help me to understand _file_

Linlin — Mon, 09 Apr 2012 22:51:55 GMT

Thank you Mike for the information! - Linlin

Re: help me to understand _file_

art297 — Mon, 09 Apr 2012 22:56:13 GMT

http://support.sas.com/rnd/base/datastep/dsv7-sugi.pdf