## Converting week and year variables to MM/DD/YYYY

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Occasional Contributor
Posts: 14

# Converting week and year variables to MM/DD/YYYY

I have variables in my data set for both the week number and year number.  I am looking for a way to convert them to a date column (MM/DD/YYYY or similar format).  I know how to convert from a date to week/year, but not vice versa.  Does anyone have any ideas?

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Solution
‎07-16-2013 10:45 AM
Super Contributor
Posts: 578

## Re: Converting week and year variables to MM/DD/YYYY

You might be able to use date math to get to the first day of the week

FirstOfWeek = mdy(1,1,yearnum) + (7 * ( weeknum - 1));

or

intnx('week',mdy(1,1,yearnum),weeknum-1);

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Super User
Posts: 24,003

## Re: Converting week and year variables to MM/DD/YYYY

WeekW. informat

Here's one way, but probably not the neatest:

(EDIT: I've assumed the day to be 1, the first of the week, but you could change that by changing the 01 and the end of week_year)

data have;

input year week ;

cards;

2001    23

2001    24

2003    45

2014    5

2005    36

2006    45

2007    3

;

run;

data want;

set have;

week_year=compress(year||"W"||put(week, z2.)||"01");

date_want=input(week_year, weekw9.);

format date_want date9.;

run;

Solution
‎07-16-2013 10:45 AM
Super Contributor
Posts: 578

## Re: Converting week and year variables to MM/DD/YYYY

You might be able to use date math to get to the first day of the week

FirstOfWeek = mdy(1,1,yearnum) + (7 * ( weeknum - 1));

or

intnx('week',mdy(1,1,yearnum),weeknum-1);

Occasional Contributor
Posts: 14

## Re: Converting week and year variables to MM/DD/YYYY

That was really helpful.  Thanks to both of you!

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