Date:         Thu, 14 Feb 2008 14:57:52 -0600
Reply-To:     Mary <mlhoward@avalon.net>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Mary <mlhoward@AVALON.NET>
Subject:      Need more elegant approach to substring problem
Content-Type: text/plain; charset="iso-8859-1"

Hello all,

I need a better solution!

Would anyone have a less tedious solution to this code?  I've got a haplotype coded as a string of 0, 1, 2.  If the character is a 0, then I want to substitute the first character of the target allele twice (i.e. Homo for Allele 1), if it is a 1, then I use the first and second character (Hetero), and if it is a 2, then use the second of the target alleles twice (Home for Allele 2). 

This works, but I'd like to make it generalizable up to at least 40 characters of the haplotype (and thus the target allele field would have exactly twice that).

-Mary

data have;

informat haplotype $40. target_alleles $80.;

infile cards;

input haplotype target_alleles;

cards;

11100110 GTCTCTATGTGTATCTCTAGATGTAGACAG

02000200 GTCTCTATGTGTATCTCTAGATGTAGACAG

01010011 GTCTCTATGTGTATCTCTAGATGTAGACAG

11100110 GTCTCTATGTGTATCTCTAGATGTAGACAG

02002102 GTCTCTATGTGTATCTCTAGATGTAGACAG

00000020 GTCTCTATGTGTATCTCTAGATGTAGACAG

run;

data need;

    informat haplotype1 $2. haplotype2 $2. haplotype3 $2. new_haplotype $80.;

    set have;

    if length(haplotype) >= 1 then

    do;

        if substr(haplotype,1,1)='0' then

            haplotype1= substr(target_alleles,1,1) || substr(target_alleles,1,1);

        else if substr(haplotype,1,1)='1' then

            haplotype1=substr(target_alleles,1,1) || substr(target_alleles,2,1);

        else if substr(haplotype,1,1)='2' then

            haplotype1= substr(target_alleles,2,1) || substr(target_alleles,2,1);

    end;

else 

    haplotype1= ' '; 

if length(haplotype) >= 2 then

    do;

        if substr(haplotype,2,1)='0' then

            haplotype2= substr(target_alleles,3,1) || substr(target_alleles,3,1);

        else if substr(haplotype,2,1)='1' then

            haplotype2= substr(target_alleles,3,1) || substr(target_alleles,4,1);

        else if substr(haplotype,2,1)='2' then

            haplotype2= substr(target_alleles,4,1) || substr(target_alleles,4,1);

      end;

else 

    haplotype2= ' '; 

if length(haplotype) >= 3 then

    do;

        if substr(haplotype,3,1)='0' then

            haplotype3= substr(target_alleles,5,1) || substr(target_alleles,5,1);

        else if substr(haplotype,3,1)='1' then

            haplotype3= substr(target_alleles,5,1) || substr(target_alleles,6,1);

        else if substr(haplotype,3,1)='2' then

            haplotype3=substr(target_alleles,6,1) || substr(target_alleles,6,1);

    end;

else 

    haplotype3= ' '; 

new_haplotype=haplotype1 || haplotype2 || haplotype3;

run;