How to get the first day of a week

[Guinaba]

Hi all,

Based on the data set below, I would like to have another col (Commence_Day) getting the date of first day of the week col(Week).

For example:

Week                  Commence_Day

Week31                    29/07/13

Week32                    05/08/13

Week33.                   12/08/13

Any suggestion?

Week	COL1	COL2	COL3	COL4	COL5	COL6	COL7	COL8	COL9	COL10	COL11
Article	4036	4036	4193	4193	4193	4193	4193	4193	4193	9585	9585
Week31	180	1380	528	552	108	324	108	192	408	4305	480
Week32	192	2496	816	804	240	384	384	144	648	6105	810
Week33	180	2340	696	696	180	408	312	192	576	5130	600
Week34	120	2304	732	804	192	420	348	168	636	4725	360
Week35	240	2280	936	780	192	504	384	240	828	5670	720
Week36	192	1800	1008	1296	240	648	588	264	996	6105	660
Week37	48	300	288	336	84	156	108	96	372	1110	255

[Patrick]

The SAS calendar function intnx() will allow you to shift a week to wherever you want to. BUT: You need a SAS date value as starting point for this.

intnx('week',<sas date value>,0,'b') would give you the Sunday the week starts, intnx('week.2',<sas date value',0,'b') would give you the Monday.

The issue with your data is: You don't have a SAS date value. Your variable "Week" doesn't even say in which year this week is  - which is kind of important to come up with the correct date. So to get from your data containing a string for a week number to a date some coding will be required. The data you've provided is not sufficient to do this. We need at least the year as well.

Just as an idea:

- Create a new variable with has the year and week in it, eg. WeekYear with values like '2013Week1'

- Create a data set to be used to create an informat (look up in docu: Proc Format with cntlin). The data set would have the WeekYear values in the Start variable and the SAS date values as label.

- Apply the informat on your WeekYear variable to populate a new variable containing SAS date values as required

[Guinaba]

Thank you Patrick!! I will follow your suggestions to correct this data set!! Much appreciate it!!!