Date:         Wed, 6 Aug 2008 17:08:40 -0400
Reply-To:     Kevin Viel <citam.sasl@GMAIL.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Kevin Viel <citam.sasl@GMAIL.COM>
Subject:      Re: Arrays - help

On Wed, 6 Aug 2008 11:49:54 -0400, sam <samygeb@GMAIL.COM> wrote:

>Hi all
>
>I am wrestling with this problem, I am sure some body could help me. I am
>posting the question again. I have a 24 hours blood pressure data with
>measurments taken every 20 minutes. The data looks some thing like this: I
>have more than 1000 subjects.
>
>ID   SystBp   Time
>01        140        8:30 (starting time)
>01        135        8:50
>01        136        9:10
>.   .  .
>.   .  .
>.   .  .
>01   135      8:30 (ending time- the next day)
>
>02        137        9:30 (starting time)
>02        125        9:50
>.   .  .
>.   .  .
>.   .  .
>02   135      9:30 (ending time- the next day)
>
>03        122        14:50 (start time)
>03        130        15:10
>03        134        15:30
>.   .  .
>.   .  .
>.   .  .
>03   137      15:50 (ending time- the next day)
>
>I want to derive variables 24 hour mean systbp, mean systbp every 3 hours
>and mean daytime systbp and nighttime bp in such away that the newly
>derived dataset is one observation pre subject.
>
>The desired output
>
>Id  24hmean  systbp3 systbp6 systbp9... systbp24 daytimebp nighttimebp
>01  127.5    130.5   .           .      .        .         .
>02  135.8    125.6   .           .      .        .         .
>03  140.9    124.7   .           .      .        .         .
>
>I tried to use arrays to solve the problem but I have no luck so far.
>
>Thank you
>sam


Hmmm.  Why not post your attempts?  It is one way to get criticism.

We do not have the advantage of knowing whether TIME is set for each
subject.


/* UNTESTED */
data one ;

  array BP_   ( 24 ) ;
  array BP_3_ ( 8  ) ;

  i_3 = 0 ;

  do _n_ = 1 by 1 until ( last.ID ) ;
    set BP_24 ;
    by ID ;

    BP_( _n_ ) = systbp ;

    if mod( time - "8:30"t , 3 ) = 0 then
      do ;
         i_3 + 1 ;
         BP_3_( i_3 ) = systbp ;
      end ;

  end ;

  do _n_ = 1 to _n_ ;
    _24_sum + BP_( _n_ ) ;
  end ;

  _24_mean = _24_sum / ( _n_ - 1 ) ;

  do _n_ = 1 to dim( BP_3_ ) ;
    _3_sum + BP_3_( _n_ ) ;
  end ;

  _3_mean = _3_sum / ( _n_ - 1 ) ;


run ;


HTH,

Kevin