Date: Fri, 1 Sep 2006 14:34:45 -0700
Reply-To: Arthur Tabachneck <art297@NETSCAPE.NET>
Sender: "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From: Arthur Tabachneck <art297@NETSCAPE.NET>
Organization: http://groups.google.com
Subject: Re: OT: RE: Select column names based on the column values
In-Reply-To: <BAY123-F3081C54074E150CBCC495CDE3C0@phx.gbl>
Content-Type: text/plain; charset="iso-8859-1"
Toby,
You still have to remember that a number of us who are SAS users are
precisely that, users, not programmers. And, for many of us, the
ability of the macro language to let us do more with fewer keystrokes
is not in any way an attempt to get out of the kitchen too quickly or
skimping on anything.
Take a revision to your example:
%macro Print;
Proc Print;
Run ;
%mend;
data one;
input x y;
cards;
1 2
3 4
;
run;
%print
If we are using such a macro for our own purpose (in the present case
to print the most recently created file), then such a simple macro
requires fewer keystrokes, allows us more time to do the research and
analyses we are being paid to do, and often lets us quickly go beyond
both the built-in SAS capabilities we know about, as well as accomplish
tasks that need features which exist but are unknown to the particular
user.
Such macro use, like above, also has the benefit of leaving less chance
of user error in specifying all of the parameters which you feel that a
good program should require.
Of course, I disagree!
Art
But, that said, do (and this goes for everyone .. including Toby) have
a nice, long holiday weekend.
---------------
toby dunn wrote:
> Jack ,
>
> It means you have a design flaw in your macro design and/or program. Pretty
> broad statement huh!!! It is true though. To be more specific it generally
> means your design is too closely tied to the data and you havent abstracted
> the problem out enough.
>
> Think about it this way, good macro design requires that it be abstracted
> enough from the data and data structure such that it has resuability. This
> reusability is what gives a macro its power to do both good and
> unfortunantly bad. The question of parameters comes down to what drives the
> macro itself. Which is meta data that cant be derived by the macro itself
> and still stay abstracted from the data and/or data structure. At the very
> least it should have a parameter passing the data set name to use.
>
>
> Lets consider a very simple example:
>
> %Macro PrintIt ;
> Proc Print
> Data = XYZ ;
> Run ;
> %Mend PrintIt ;
>
> Okay this is a very simple macro but the problem with it is the fact that it
> is perfectly tied to the data XYZ. Not very useful when you need to print
> different data sets. Also it is no different than if you didnt have the
> macro wrapper. In essence you have to change the inner working of the macro
> inorder to make it usefull for some other data set.
>
> So lets rewrite it something like:
>
> %Macro PrintIt( DataIn = ) ;
> Proc Print
> Data =&DataIn ;
> Run ;
> %Mend PrintIt ;
>
> Now we can just call the macro as much as we want no problems fiddling with
> the its innards.
>
> We could have just as easily done the following:
>
> %Macro PrintIt ;
> Proc Print
> Data =&DataIn ;
> Run ;
> %Mend PrintIt ;
>
> No parameter but it also means the user has to know that the macro requires
> a global macro variable called Datain. This is a train wreck waiting to
> happen for so many reasons that have been stated so many time already on
> SAS-L.
>
> You specifically mentioned %If-%then statements. Okay fair enough.... The
> values for them to compare too have to come from somewhere. The question
> you need to ask is where should they come from and when? These values must
> come from either a step before the %If-%Then or they must come from
> somewhere outside of the macro. If it is the former then the intial data
> set name needs to be passed in as a parameter. Then pass the %If-%Then
> Values in as parameters.
>
> Now having said all of this and waiting for Ian to come in and beat me about
> my head and upper thorax region with his corrections. One can make a case
> for a System D type programming approach. System D is a culinary term used
> to refer to a cook who is willing to cut a few but not all corners, to avoid
> or get a kitchen out of the weeds during a rush. In programming terms it is
> a mercenary type programmer who in the thick of things with looming dead
> lines, bosses who are all up in there face about getting this project turned
> out ASAP (mainly due to the bosses inability to set doable deadlines), or
> simply helping another programmer out of the weeds is able to step in and
> cut a few corners here or there use a few tricks of the trade and get the
> deliverables out the door. In these cases it may be advantagous to simply
> say the hell with proper design and just bang out the code in what ever way
> they can get it too work.
>
> Toby Dunn
>
> When everything is coming at you all at once, your in the wrong lane.
>
> A truly happy person is someone who can smile and enjoy the scenery on a
> detour.
>
>
>
>
>
> From: Jack Clark <JClark@CHPDM.UMBC.EDU>
> Reply-To: Jack Clark <JClark@CHPDM.UMBC.EDU>
> To: SAS-L@LISTSERV.UGA.EDU
> Subject: OT: RE: Select column names based on the column values
> Date: Fri, 1 Sep 2006 13:09:34 -0400
>
> Toby,
>
> I sometimes use macro programs with no parameters to take advantage of the
> macro language statements (%IF-%THEN, conditionally executing PROCS, etc.).
>
> What is it that you hate about macros without parameters? Is it a personal
> preference thing, or is there something I could learn about programming
> clarity or efficiency?
>
> Thanks.
>
>
> Jack Clark
> Research Analyst
> Center for Health Program Development and Management
> University of Maryland, Baltimore County
>
> -----Original Message-----
> From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On Behalf Of toby
> dunn
> Sent: Friday, September 01, 2006 12:24 PM
> To: SAS-L@LISTSERV.UGA.EDU
> Subject: Re: Select column names based on the column values
>
> Sekhar ,
>
> I will offer a slightly different perspective here in so much as I dont like
> writing macros when I feel one isnt needed and I especially hate macros that
> among other things have no parameters.
>
>
> So here is my humble non-macro solution:
>
> Data Test ;
> Input Col1 Col2 Col3 ;
> Cards;
> 23 40 30
> -100 30 40
> 25 -100 35
> ;
> Run ;
>
> ODS Listing Close ;
> ODS Output OneWayFreqs = Freqs ;
>
> Proc Freq
> Data = Test ;
> Table _Numeric_ ;
> Run ;
>
> ODS Listing ;
>
> Data VarNames ( Keep = VarNames ) ;
> Length VarNames $ 200 ;
> Set Freqs ;
> By Table ;
>
> If ( First.Table And ( VValueX( Scan( Table , 2 , ' ' ) ) = -100 ) ) ;
>
> VarNames = Scan( Table , 2 , ' ' ) ;
>
> Run ;
>
>
> Proc SQL NoPrint ;
> Select VarNames Into: Vars Separated By ','
> From VarNames ;
>
> Create Table New As
> Select &Vars
> From Test ;
> Quit ;
>
> Proc Print
> Data = New ;
> Run ;
>
>
> Toby Dunn
>
> When everything is coming at you all at once, your in the wrong lane.
>
> A truly happy person is someone who can smile and enjoy the scenery on a
> detour.
>
>
>
> -----Original Message-----
> From: SAS(r) Discussion [mailto:SAS-L@LISTSERV.UGA.EDU] On Behalf Of Sekhar
> Sent: Friday, September 01, 2006 10:40 AM
> To: SAS-L@LISTSERV.UGA.EDU
> Subject: Select column names based on the column values
>
> Hi
> How can I select the coulmn names based on the column values.
> For example
> col1 col2 col3
> 23 40 30
> -100 30 40
> 25 -100 35
>
> In this I want to select all the column names having minimum value of
> -100. can I use sashelp.vcolumn.
>
> Thanks for the help.
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