Appending specific year to an extracted month and day

[gabagotati]

I have a dataset with unique IDs and date of births, and I would like to calculate their age from future birthdays in specific years (for example, 2018 and 2019). I understand how to calculate age between two dates, but am having trouble with creating the dates of the future birthdays  in the first place. In other words, I'd like to take the month and day of their birthday, and append to a specified year.

Have:

ID_1                  DOB               

A2543              08OCT1993             

A3667              12JUL2003             

A3624              30MAR2000             

Want:

ID_1                  DOB                    bday_2018        bday_2019           age_2018      age_2019

A2543              08OCT1993          08OCT2018      08OCT2019              26                   27

A3667              12JUL2003           12JUL2018        12JUL2019               15                   16

A3624              30MAR2000         30MAR2018      30MAR2019              18                    19

[Astounding]

You're making this way more difficult than it needs to be.  If you want to use the same day and month, you don't have to use month and day.  You need one of these:

age_2018 = 2018 - year(dob);

Looking at the calculations you have already made, you may be looking at a variation:

age_2018 = 2018 + 1 - year(dob);

But I would expect the first formula is the correct one.

[gabagotati]

Thanks for you response. The reason I am interested in extracting the specific month and day is that is I have another variable (date of enrollment), and I'd like to find their age at this date.

For A2543 in my example, they are 18 after their birthday of 08OCT2018 and before their next birthday 08OCT2019. If their enrollment date was on 01JUN2019, they would be 18 on this day. Your solution would yield age_2019 of 19, which would not be what I want.

Apologies for not including this piece in my original post.    

[ballardw]

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@gabagotati wrote:

Thanks for you response. The reason I am interested in extracting the specific month and day is that is I have another variable (date of enrollment), and I'd like to find their age at this date.

For A2543 in my example, they are 18 after their birthday of 08OCT2018 and before their next birthday 08OCT2019. If their enrollment date was on 01JUN2019, they would be 18 on this day. Your solution would yield age_2019 of 19, which would not be what I want.

Apologies for not including this piece in my original post.    

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If you have another DATE valued variable then the YRDIF function may  be what you want:

ageatdate = floor( yrdif(dob,enrollmentdate) );

This will return a decimal portion. So you may want to use the FLOOR function to remove the decimal bit:

[PaigeMiller]

I think you have chosen a poor layout of the data to do this. A better layout would be

Want:

ID_1                  DOB                    year                                                   age

A2543              08OCT1993         2018                                                   26                  

A2543              08OCT1993         2019                                                   27

A3667              12JUL2003          2018                                                   15

A3667              12JUL2003          2019                                                   16

---

@gabagotati wrote:

Thanks for you response. The reason I am interested in extracting the specific month and day is that is I have another variable (date of enrollment), and I'd like to find their age at this date.

For A2543 in my example, they are 18 after their birthday of 08OCT2018 and before their next birthday 08OCT2019. If their enrollment date was on 01JUN2019, they would be 18 on this day. Your solution would yield age_2019 of 19, which would not be what I want.

Apologies for not including this piece in my original post.    

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However, to address the problem you now state, I make up some data and address the solution.

data have;
input ID $ DOB :date9. date_of_enrollment :date9.;      
cards;
A2543 08OCT1993 01JUN2019                
A3667 12JUL2003 12JUL2020   
A3624 30MAR2000 19JAN2021
;

data want;
    set have;
    age_at_enrollment = intck('year',dob,date_of_enrollment,'c');
run;