UNIX for Dummies Questions & Answers

Hello,
I have the following data set:
TRAIT DOSE
40 0.4
30 0.3
95 1.2
120 1.7
85 1.4
136 1.8
134 1.8
40 0.4
30 0.3
95 1.2
120 1.7
85 1.4
136 1.8
134 1.8
40 0.4
30 0.3
95 1.2

I want to code a new variable this way. For the Dosage column, say I call it D_GROUP, I would like to group the dosages into 3 distinct groups, that is to say,
Dosage Levels will be
Group1 : 0.0-0.49 including all values more than 0 but less than 0.5
Group2: 0.5-1.49: including all values equal to or more than 0.5 but less than 1.5
Group3: 1.5-2: including all values equal to or more than 0.5 but less than 2

Essentially, I would like my final file to look like this:
TRAIT DOSAGE GROUP
40 0.4 0.0-0.49
30 0.3 0.0-0.49
95 1.2 0.5-1.49
120 1.7 1.5-2
85 1.4 0.5-1.49
136 1.8 1.5-2
134 1.8 1.5-2
40 0.4 0.0-0.49
30 0.3 0.0-0.49
95 1.2 0.5-1.49
120 1.7 1.5-2
85 1.4 0.5-1.49
136 1.8 1.5-2
134 1.8 1.5-2
40 0.4 0.0-0.49
30 0.3 0.0-0.49
95 1.2 0.5-1.49


How do I do this? Please help!
Thank you!

You can try using awk, store the values in an array on your first entry of the file, then read the file again and print the values. Not complete but will give you an idea.

Outputting the results of each range to a separate file and then joining them together will be more efficient.

Code:

BEGIN {
  ARGV[ARGC] = ARGV[ARGC-1]                                    # Read file twice
  ARGC++
  i=1
  j=1
}

FNR == NR {

  if ($2 >= 0.0 || $2 <= 0.49) {
    range1[i] = $0
  }

  if ($2 >= 0.5 || $2 <= 1.49) {
    range1[j] = $0
  }

  i = i++
  j = j++

  next

}

FNR > NR {
  print range1[m] 
}

Code:

$ cat grp.awk
BEGIN { split("0.0:0.5:1.5:2", A, ":"); }

{       for(N=1; A[N+1]; N++)
        if(($2 >= A[N])&&($2 < A[N+1]))
        {
                MAX=A[N+1];
                if(A[N+2]) MAX-=0.01;
                $3=sprintf("%.2f-%.2f", A[N], MAX);
                break;
        }
} 1

$ awk -f grp.awk data

40 0.4 0.00-0.49
30 0.3 0.00-0.49
95 1.2 0.50-1.49
120 1.7 1.50-2.00
85 1.4 0.50-1.49
136 1.8 1.50-2.00
134 1.8 1.50-2.00
40 0.4 0.00-0.49
30 0.3 0.00-0.49
95 1.2 0.50-1.49
120 1.7 1.50-2.00
85 1.4 0.50-1.49
136 1.8 1.50-2.00
134 1.8 1.50-2.00
40 0.4 0.00-0.49
30 0.3 0.00-0.49
95 1.2 0.50-1.49

$