Date: Mon, 31 Oct 2005 22:39:28 +0000
Reply-To: iw1junk@COMCAST.NET
Sender: "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From: Ian Whitlock <iw1junk@COMCAST.NET>
Subject: Re: proc format value assignment oddity - missing values
Paul,
I see you have some good answers. I think several years ago Peter Lund
gave a SUGI paper on formats in which he discussed the problem. Over the
years I have developed the following conventions for using quote marks in
SAS.
1) Never use single quotes unless you have to, i.e. to hide macro
triggers. (65% doesn't matter, 30% either matters or will when
modified, 5% must be single quotes and they will stick out as
important.)
2) Never use "" to mean " " - usually they mean the same in SAS, but
not always. (options formdlim=""; and inside double quotes are some
other cases.)
The reason that it did not matter whether you used one blank or multiple
blanks comes from the fact that SAS character variables have a fixed length
space filled when a value is short. The function TRIM would be needed far
more often in SAS code without the convention that trailing blanks compare
equal.
Ian Whitlock
================
Date: Sun, 30 Oct 2005 10:47:27 -0800
Reply-To: pchoate <paulchoate61@YAHOO.COM>
Sender: "SAS(r) Discussion"
From: pchoate <paulchoate61@YAHOO.COM>
Organization: http://groups.google.com
Subject: proc format value assignment oddity - missing values
Comments: To: sas-l
Content-Type: text/plain; charset="iso-8859-1"
Question for proc freq wonks -
Generally, missing character values in SAS can be represented by either
'' (no blanks), ' ' (single blank), or ' ' (many blanks). In
comparisons there usually aren't any functional differences between
them. The way I think about it is that a character variable must be a
least length 1, and trailing blanks are ignored, and so all blank
values are treated as ' ', and SAS internally equates '' with ' ', and
so any comparison of two missing character values equate regardless of
length.
I was looking at the distribution of missing values in some data and so
coded the following format and freq:
proc format;
value $MISS '' = 'Missing'
other = 'Not Msg';
proc freq ;
tables clientid*age / missing;
format clientid age $miss.;
run;
Although the Age column had missing values they weren't shown - the
blanks equated to 'Not Msg', and so found that in Proc Freq '' does not
equate to ' '.
I tried:
proc format;
value $MISS ' ' = 'Missing' /* note the blank */
other = 'Not Msg';
proc freq ;
tables clientid*age / missing;
format clientid age $miss.;
run;
I got the expected results. I also tried more blanks than would equate
and they matched as expected:
proc format; /* age is $5 client is $9 */
value $MISS ' ' = 'Missing'
other = 'Not Msg';
proc freq ;
tables clientid*age / missing;
format clientid age $miss.;
run;
On the left side of a proc format value statement assignment, does ''
have any meaning? Is it '00'x rather than '20'x?
Thanks to all that reply.
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