match index notation of file1 to the index of file2 and pull out matching rows

Question

file1 contains multiple alphabetic sequences:

AETYUIOOILAKSJ
EAYEURIOPOSIDK
RYXURIAJSKDMAO
URITORIEJAHSJD
YWQIAKSJDHFKCM
HAJSUDIDSJSIAJ
AJDHDPFDIXSIBJ
JAQIAUXCNC         


        

Answer 1

$ cat tst.awk
NR==FNR {
    lgth = length($0)
    pos2char[substr($0,1,lgth-1)] = substr($0,lgth,1)
    next
}
{
    for (pos in pos2char) {
        if ( substr($0,pos,1) == pos2char[pos] ) {
            print
            next
        }
    }
}

$ awk -f tst.awk file2 file1
AETYUIOOILAKSJ
RYXURIAJSKDMAO
URITORIEJAHSJD
JAQIAUXCNCVUFO

Answer 2

With GNU awk and grep:

awk -v FPAT='[0-9]+|[A-Z]+' '{ print "^.{" $1-1 "}" $2 }' file1 | grep -Ef - file2

Output:

AETYUIOOILAKSJ
RYXURIAJSKDMAO
URITORIEJAHSJD
JAQIAUXCNCVUFO

Answer 3

Here you go:

awk 'NR==FNR {b[$0]++;next} {for (i in b) {a=match($0,"[A-Z]");n=substr($0,1,(a-1));s=substr($0,a);t=substr(i,n,1);if (t==s) print i}}' file1 file2
AETYUIOOILAKSJ
RYXURIAJSKDMAO
URITORIEJAHSJD
JAQIAUXCNCVUFO

Some more readable:

awk '
NR==FNR {
  b[$0]++;
  next
} 
{
  for (i in b) {
    a=match($0,"[A-Z]");
    n=substr($0,1,(a-1));
    s=substr($0,a);
    t=substr(i,n,1);
    if (t==s) 
      print i
    }
}
' file1 file2

With comments:

awk '
NR==FNR {                 # For the first file
  b[$0]++;                # Store file1 in in array b
  next
} 
{
  for (i in b) {          # Loop trough elements in array b
    a=match($0,"[A-Z]");  # For file2 find where letters starts
    n=substr($0,1,(a-1)); # Store the number part of file2 in n
    s=substr($0,a);       # Store the letters part of file2 in s
    t=substr(i,n,1);      # from file1 find string at position n
    if (t==s)             # test if string found is equal to letter to find s
      print i             # if yes, print the line 
    }
}
' file1 file2

Answer 4

awk '(NR==FNR){a[$0]=substr($0,length);next}
     { for(key in a) if (a[key] == substr($0,key+0,1)) { print; break }
     }' file2 file1

Here, the array a[key] is a associative array with the following key-value pairs:

key:   value
3T     T
10K    K
...    ...

When processing file2 with the line: (NR==FNR){a[$0]=substr($0,length);next}: we extract the value beforehand so we don't have to do it later on. The index is easily extracted with a math operation. Eg. "10K"+0=10 in Awk.

Processing file1 is done with the next line. Here we just check if the character matches for any of the entries in the associative array.

Answer 5

With awk + grep pipeline:

awk '{ pat=sprintf("%*s", int($0)-1, ""); gsub(" ", ".", pat); 
       printf "^%s%s\n", pat, substr($0, length) }' file2 | grep -f- file1

The output:

AETYUIOOILAKSJ
RYXURIAJSKDMAO
URITORIEJAHSJD
JAQIAUXCNCVUFO