topic Re: Using information in previous observations in SAS Programming

Using information in previous observations

brunosm — Mon, 14 Mar 2016 15:19:28 GMT

Hello guys,

I have a question for you that I am able to solve in Excel or R, but I'm not seeing how can I do it in SAS.

Let's suppose that I have this dataset:

ID	Simulated	Date	Error_flag
1	0	Dec2013	Error
1	1	Jan2014
1	1	Feb2014
1	1	Mar2014
1	0	Apr2014
1	1	May2014
1	1	Jun2014
1	1	Jul2014
2	0	Jan2014
2	1	Feb2014
2	1	Mar2014
2	0	Apr2014	Error
2	1	May2014
2	1	Jun2014
2	0	Jul2014
2	1	Aug2014

I would like to create a new column, New_error_flag, if the following conditions were verified:

a) for each id, if simulated = 0 and error_flag = "Error", then New_error_flag = "Error" and all the observations with following dates and simulated = 1 also get New_error_flag = "Error"

b) if simulated = 0 and error_flag = "", then all the following observations with posterior date and simulated=1 gets New_error_flag =""

Sorry for my english, let me show you the final result:

ID	Simulated	Date	Error_flag	New_error_flag
1	0	Dec2013	Error	Error
1	1	Jan2014		Error
1	1	Feb2014		Error
1	1	Mar2014		Error
1	0	Apr2014
1	1	May2014
1	1	Jun2014
2	0	Jan2014
2	1	Feb2014
2	1	Mar2014
2	0	Apr2014	Error	Error
2	1	May2014	Error	Error
2	1	Jun2014	Error	Error
2	0	Jul2014
2	1	Aug2014

Can you help me?

Thanks a lot,

Brunosm

Re: Using information in previous observations

ballardw — Mon, 14 Mar 2016 15:27:06 GMT

I think this should get you started:

data want;
   set have;
   length new_error_flag $ 5;
   retain new_error_flag ' ';
   if simulated=0 and error_flag='Error' then new_error_flag='Error';
   if simulated=0 and error_flag='' then call missing(new_error_flag);
run;

Re: Using information in previous observations

Reeza — Mon, 14 Mar 2016 15:28:58 GMT

Use RETAIN which tells SAS to hold the value across the different rows, until you reset it.

data want;
set have;
retain new_error_flag;

if simulated=0 then new_error_flag=error_flag;

run;

proc print data=want;
run;

Re: Using information in previous observations

brunosm — Mon, 14 Mar 2016 15:37:37 GMT

Reeza,

That's exacly what I want!

Thanks a lot! 🙂