topic Re: What's wrong with codes? in SAS Programming

What's wrong with codes?

MikeTurner — Tue, 20 Aug 2013 12:12:04 GMT

Hi Guys,

I want to rank my my data within groups, so I used lag function in my codes. But it seems this function does not work. I'm wondering why lag1(mylabel) is missing when _n_=2. Anyone could help me out? Thanks.

Mike

data cake;

input Name $ 1-10 type 12-13 Taste 15-16;

datalines;

Davis 1 84

Orlando 1 80

Ramey 1 72

Roe 2 75

Sanders 2 79

Simms 2 77

Strickland 2 79

;run;

proc sort data=cake;

by type taste;run;

data a;

set cake;

by type taste;

if type=lag1(type) then mylabel=1+lag1(mylabel);

else mylabel=1;

if _n_=1 then mylabel=1;

run;

Re: What's wrong with codes?

LinusH — Tue, 20 Aug 2013 12:32:36 GMT

Haven't investigated your lag-problem, but I am generally more convenient using first./last.logic, which I believe you could use together wit a conditional mylabel+1; (which will make mylabel automatically retained).

Re: What's wrong with codes?

esjackso — Tue, 20 Aug 2013 13:14:08 GMT

I dont think you can recursively create a variable with the lag function because the variable being created is going into the output dataset and not available to SAS PDV (I admit, I may have the SAS workings wrong here ... someone feel free to correct this).

Why do you not want to use something like the following as suggested?

data a;

set cake;

by type taste;

if first.type then mylabel=1;

else mylabel + 1;

run;

Re: What's wrong with codes?

OS2Rules — Tue, 20 Aug 2013 13:17:07 GMT

Also a RETAIN MYLABEL; ??

Re: What's wrong with codes?

data_null__ — Tue, 20 Aug 2013 14:00:22 GMT

OS2Rules wrote:

Also a RETAIN MYLABEL; ??

Would you? Did you test?

What does "sum" statement imply?

Re: What's wrong with codes?

LinusH — Tue, 20 Aug 2013 14:03:45 GMT

No need, RETAIN is implied within the var + n; construct.

Re: What's wrong with codes?

jakarman — Tue, 20 Aug 2013 20:11:52 GMT

The construction with conditions and using lag in it is confusing

The LAG function is a logical queue construct pushing the current value in and getting the oldest out of it. It is not the same as a retain.

SAS(R) 9.4 Functions and CALL Routines: Reference (LAG)

At the first time " mylabel=1+lag1(mylabel); " is called (_n_ =2) it will push a missing in the que as mylabel for that observation has not been defined. It is exactly working as has been described.