Unexpected result using informat to create numeric variable from character variable

[ABritinAus]

Hi.

One of my SAS users has asked me to explain why the code below does not do what they expect - ie create a numeric variable (newvar) which is equal to 1 when the character variable myvar has a value of D01a_tot and is missing otherwise.

Now I realise there are many workarounds to this, which I have already fedback, and also that using the informat to code just one value is probably not necessary.

But I'd still be keen to know why ALL records get assigned a value of 1 when the numeric variable is created. Clearly all the records start with "D01a_Tot" and I guess that is causing the issue.

Can anyone explain why its happening and whether it's actually not "unexpected".

Thanks!

Code below (running on SAS 9.4M3)

data temp;

length myvar $20;

myvar="D01a_Tot_D02"; output;

myvar="D01a_TotP09"; output;

myvar="D01a_TotP12"; output;

myvar="D01a_TotP15"; output;

myvar="D01a_TotP16"; output;

myvar="D01a_Tot"; output;

run;

proc format;

INVALUE my_order

"D01a_Tot" = 1;

run;

data temp2;

set temp;

newvar=input(myvar,my_order.);

run;

[LaurieF · Accepted solution]

The default length of the invalue is the length of D01a_Tot - 8, which is the length of the comparison being made on your myvar variable; everything after that is ignored.

If you change the format to

proc format;
INVALUE my_order(default=20)
"D01a_Tot" = 1
other = .;             /* Stops error messages */
run;

or the data step to:

data temp2;
set temp;
newvar=input(myvar, my_order20.);
run;

then you'll get the result you require. Note that the second suggestion doesn't stop error messages.

I would recommend the former, because you can reuse the format in all your other data steps without thinking about it.

[ABritinAus]

Thanks.

That all makes sense.

[ballardw]

The INPUT function sometimes behaves a bit differently than an input statement. Please see this:

proc format library=work;
INVALUE my_order
"D01a_Tot" = 1
other = .
;
run;
data temp;
   informat x my_order.;
   input x;
datalines;
D01a_Tot_D02
D01a_TotP09
D01a_TotP12
D01a_TotP15
D01a_TotP16
D01a_Tot
run;

Note that to assign other values such as missing it is a good idea to explicitly set that in the INVALUE so there isn't any doubt of intent.

It helps to post code into a code box opened using either the {i} or "running man" icon in this forum.

[ABritinAus]

Thanks for the prompt reply - the time zone here is handy for overnight responses

Will use that for reading in data using informats.  

And thanks for the tip re inserting the code: will note for future.

[LaurieF]

I'm only two hours (probably) ahead of you - Wellington!

Glad to have helped.