topic last three obs in SAS Programming

last three obs

BrahmanandaRao — Tue, 29 Oct 2019 05:14:30 GMT

Hi,

Experts Good Morning

Here i have a class dataset from that i want to retrieve last three observations

what if how many observations in a data set then how to get last three observations

/*if we do not know how many obs in a dataset then how we get last 3 records*/
data ds10;
do i=nobs to 1 ;
set sashelp.class point=i nobs=nobs;
output;
end;
stop;
run;

Re: last three obs

Kurt_Bremser — Tue, 29 Oct 2019 05:21:02 GMT

With what do you have to replace the "1" here

do i = nobs to 1 by -1;

to only get three observations? Play around with it.

Re: last three obs

BrahmanandaRao — Tue, 29 Oct 2019 05:25:49 GMT

do i = nobs to 1 by -1;

just come reverse order only but i want last three records

and how to do unknown observations in a dataset

Re: last three obs

Kurt_Bremser — Tue, 29 Oct 2019 06:26:14 GMT

You already know the number of observations in the dataset (nobs). So just count up from nobs - 2, or don't use point= at all, and just output when _n_ reaches your threshold.

Re: last three obs

BrahmanandaRao — Tue, 29 Oct 2019 06:54:15 GMT

Sorry not understand

Re: last three obs

Kurt_Bremser — Tue, 29 Oct 2019 07:13:04 GMT

You know the total number of observations in your dataset (that's what the nobs= option does).

The automatic variable _N_ provided by SAS holds the number of data step iterations, so in a simple data step it gives you the number of the current observation read. By comparing _N_ to nobs - 3 in a subsetting if, you can achieve what you want.

Re: last three obs

BrahmanandaRao — Tue, 29 Oct 2019 07:26:50 GMT

Sir

Here it is correct output

/*if we do not know how many obs in a dataset then how we get last 3 records*/
data ds10;
do i=nobs-2 to nobs;
set sashelp.class nobs=nobs point=i;
output;
end;
stop;
run;

Re: last three obs

Kurt_Bremser — Tue, 29 Oct 2019 07:42:51 GMT

Alternatively, with a subsetting if:

data ds10;
set sashelp.class nobs=nobs;
if _n_ > nobs - 3;
run;

With larger datasets and small subsets, the point= will perform better.

Re: last three obs

BrahmanandaRao — Tue, 29 Oct 2019 08:07:56 GMT

Thank You sir

For your quick response and advise