topic First.Variable Last.Variable to sum multiple observations in New SAS User

First.Variable Last.Variable to sum multiple observations

mariamabotaleb — Wed, 23 Dec 2020 22:44:40 GMT

Hello,

I am trying to sum multiple observations with the First.Variable Last.Variable feature, however it never works in adding all the observations together, it either gives me the first or last variable values

Data T_Total;
set T;
by m**;
if first. m** then TOTAL_DAYS=0;
TOTAL_DAYS= sum (TOTAL_DAYS,SUPPLY_DAYS);
retain TOTAL_DAYS;
if last. m** then output;
run;

I also tried changing the order of sentences, or using the

TOTAL_DAYS= TOTAL_DAYS+SUPPLY_DAYS;

Re: First.Variable Last.Variable to sum multiple observations

PaigeMiller — Thu, 24 Dec 2020 00:50:39 GMT

There's no double-asterisk in this syntax.

And instead of TOTAL_DAYS=sum (TOTAL_DAYS,SUPPLY_DAYS); you probably want

total_days+supply_days;

Better yet, don't program this yourself in a DATA step. Use PROC SUMMARY, where this is a built-in feature.

Re: First.Variable Last.Variable to sum multiple observations

Astounding — Thu, 24 Dec 2020 02:30:45 GMT

When you use first. and last. variables, there should not be a space after the dot. Incorrect:

first. m

Correct:

first.m

And as was noted, asterisks are not a legitimate part of a variable name. Clean up the obvious inaccuracies, and see if any problems remain. Your syntax for summing should work, even if other choices exist.

Re: First.Variable Last.Variable to sum multiple observations

Tom — Thu, 24 Dec 2020 05:03:05 GMT

Make sure that TOTAL_DAYS does not already exist as a variable in the input dataset T. Because if it does then as you read observations from T the value you calculated after reading the pervious observation will be overwritten with what is read from T.