topic Re: Difference in date when one date column has NA in SAS Data Management

Difference in date when one date column has NA

StarMan — Wed, 14 Mar 2018 19:09:13 GMT

I am trying to compute the difference in dates based on the date values in two columns and store the results in a third column. The dataset I have looks like this below.

  Id      Col1_Date          Col2_Date
  1       2009-09-10         1916-02-29
  1       2009-09-10         NA

The expected output should be

  Id      Col1_Date          Col2_Date      Date_Diff
  1       2009-09-10         1916-02-29     93.6
  1       2009-09-10         NA             NA

I have tried a simple DataSet as shown below, but this is not working. I am not seeing any values in Date_Diff column.

  DATA  WORK.DF1 ;
  SET   WORK.DF1 ;
  FORMAT DOB date10.;
  Date_Diff = Col1_Date - Col2.Date;
  RUN;

Any help or suggestions on achieving this is much appreciated.

Re: Difference in date when one date column has NA

Reeza — Wed, 14 Mar 2018 19:13:00 GMT

Are the dates SAS dates, ie numeric with a format such as yymmdd or are they character variables?

If they're character you first have to convert them to a number/numeric to do calculations.

@StarMan wrote:

I am trying to compute the difference in dates based on the date values in two columns and store the results in a third column. The dataset I have looks like this below.
  Id      Col1_Date          Col2_Date
  1       2009-09-10         1916-02-29
  1       2009-09-10         NA
The expected output should be
  Id      Col1_Date          Col2_Date      Date_Diff
  1       2009-09-10         1916-02-29     93.6
  1       2009-09-10         NA             NA
I have tried a simple DataSet as shown below, but this is not working. I am not seeing any values in Date_Diff column.
  DATA  WORK.DF1 ;
  SET   WORK.DF1 ;
  FORMAT DOB date10.;
  Date_Diff = Col1_Date - Col2.Date;
  RUN;
Any help or suggestions on achieving this is much appreciated.

Re: Difference in date when one date column has NA

PaigeMiller — Wed, 14 Mar 2018 19:15:32 GMT

Great ... but you haven't told us what you do see so we can compare it to the expected output. We need that.

As a potential source of problems, your syntax is wrong here:

Date_Diff = Col1_Date - Col2.Date;

It should say

Date_Diff = Col1_Date - Col2_Date;