Date Difference

[Eugenio211]

Hi - I'm trying to get the date difference (number of days) of the loan dates of each customer.  The idea is to get the number of days: loan 1 - loan 2, then loan 1 - loan 3, and then loan 1 - loan 4.

below is my example data:

CUSTOMER	LOAN #	LOANDATE	Date Diff
Cust A	1	4-Jan-20
Cust A	2	11-Feb-20
Cust A	3	27-Mar-20
Cust A	4	4-Apr-20
Cust B	1	21-Jun-20
Cust B	2	18-Jul-20
Cust B	3	15-Aug-20
Cust B	4	9-Sep-20

Thank you so much!

[novinosrin]

Hi @Eugenio211  An expected sample of output would help, or do you mean this?-

data have;
input CUSTOMER & $12.	LOAN 	LOANDATE :date9.;
format loandate date9.;
cards;
Cust A	1	4-Jan-20	 
Cust A	2	11-Feb-20	 
Cust A	3	27-Mar-20	 
Cust A	4	4-Apr-20	 
Cust B	1	21-Jun-20	 
Cust B	2	18-Jul-20	 
Cust B	3	15-Aug-20	 
Cust B	4	9-Sep-20
;

data want;
 set have;
 by customer;
 if first.customer then _iorc_=loandate;
 else datediff=intck('day',_iorc_,loandate);
run;

CUSTOMER	LOAN	LOANDATE	datediff
Cust A	1	04JAN2020	.
Cust A	2	11FEB2020	38
Cust A	3	27MAR2020	83
Cust A	4	04APR2020	91
Cust B	1	21JUN2020	.
Cust B	2	18JUL2020	27
Cust B	3	15AUG2020	55
Cust B	4	09SEP2020	80

[me55]

hi eugenio...

i think you have two issues, how to select the dates then how to subtract them.  

so, you can use into to put a loan into a variable and use it later so...

proc sql;

select LOANDATE

    into :LNDT01

  from TABLE

  where CUSTOMER=CUSTA and LOAN=1;

quit;

so that puts it into a variable LNDT01 and using that you can put each date into a variable like that then to subtract them, here is a page describing that...

SAS Doc Date Intervals 

by combing that, you can do what you are looking for.  

[Tom]

SAS stores dates as number of days. So to find the difference in days just subtract.

To find the difference between observations you can use the DIF() function.  

Since you have different CUSTOMERs you need to use BY group processing.  Is it important to run DIF() on every observation.  So find the difference first and then set it missing when you are starting a new customer.

data want;
  set have;
  by customer loan_number;
  date_diff = dif(loandate);
  if first.customer then date_diff=.;
run;