topic Re: Converting a Sequence to Monotonically Increasing Sequence in SAS Programming

Converting a Sequence to Monotonically Increasing Sequence

hansmuller — Wed, 17 Jun 2020 08:01:38 GMT

Hi, I have a variable X with the sequence of number such as: 3, 4, 6, 5, 4, 7, 9, 7, 8, 9, 10. I need to create a new variable Y so that Yi=max(Xi, Yi-1). It would become a sequence like: 3, 4, 6, 6, 6, 7, 9, 9, 9, 9, 10. How can I do the programming to get this new variable? Thank you so much for your suggestion.

Re: Converting a Sequence to Monotonically Increasing Sequence

FreelanceReinh — Wed, 17 Jun 2020 08:20:14 GMT

Hi @hansmuller,

Apply the RETAIN statement to y:

data have;
infile cards dsd;
input x @@;
cards;
3, 4, 6, 5, 4, 7, 9, 7, 8, 9, 10
;

data want;
set have;
y=max(x,y);
retain y;
run;

Re: Converting a Sequence to Monotonically Increasing Sequence

ed_sas_member — Wed, 17 Jun 2020 08:29:58 GMT

Hi @hansmuller

I am thinking about something like this, using the RETAIN function:

data want;
	set have;
	retain y;
	if x >= y then y=x;
run;

Re: Converting a Sequence to Monotonically Increasing Sequence

Jagadishkatam — Wed, 17 Jun 2020 10:58:06 GMT

Alternatively with ifn and retain

data want;
set have;
retain new;
new=ifn(x<new,new,x);
run;

Re: Converting a Sequence to Monotonically Increasing Sequence

hansmuller — Wed, 17 Jun 2020 15:09:27 GMT

Thank you so much!