Using Lag Properly

[deleted_user]

Hello,

I have the following data:
input_table (ordered by customernumber, code number):

customernumber code_number

1 a1
1 b1
1 c1
2 a1
2 c1
3 c1


I'd like to use lag to look 2 rows prior, determine if the customernumber is the same for the prior 2 customernumber rows, then look at the code number, and determine if I'm on code number c1, and if so look back at the 2 prior code number rows are a1 and b1. If so, this meets the criteria I'm looking for. As an example, customernumber 1 is the only one above that matches this criteria. I'm using the following SAS code to do this, using lag. Please let me know if this looks good, thx!


libname sassvrtable 'my/sasdatabase/table'
data output_data;
set sassvrtable.input_table;

\*prev custnumber*\
lag_data_custnum = lag(customernumber);

\*2nd prev custnumber*\
lag_data_custnum2 = lag(lag_data_custnum);

\*prev codenumber*\
lag_code_number = lag(code_number);
\*2 prev codenumber*\
lag_code_number_2 = lag(lag_code_number);

\*IF MEETS MY CRITERIA*\
if lag_data_custnum = customernumber
and lag_data_custnum2 = customernumber
and code_number = c1
and lag_code_number = b1
and lag_code_number_2 = a1
then match = 'TRUE';

Proc Print data = output_data;
run;

[milts]

Hi Scott,

Try using lag2 instead of lag

Milton

[deleted_user]

Thank you, this will work.