Finding Line sequence

bufsn · #1 (**permalink**) 06-15-07, 11:05

Hi,
I have a file like the following with altername lines starting with 'H' and 'S'

H0102.........
SLSC10299......
H0103.........
SLSC10299......
H0104.........
SLSC10299......

I want to delete all the 'H' and 'S' line which are not occuring in the above sequence
for eg, I want to delete the third line in the following
H0102.........
SLSC10299......
H0103.........
H0104.........
SLSC10299......

I want to delete the fifth line in the following
H0102.........
SLSC10299......
H0103.........
SLSC10299......
SLSC10299......
H0104.........
SLSC10299......
Can anyone please help?
Thanks.

aigles · #2 (**permalink**) 06-15-07, 11:51

You can do something like that (if you are sue that lines start only with H or S) :

Code:

$ cat lseq.txt
H0102.........
SLSC10299......
H0103.........
H0104.........
SLSC10299......
SLSC10299......
H0104.........
SLSC10299......
$ awk -v seq=x '$0 !~ "^" seq { print; seq=substr($0,1,1) }' lseq.txt
H0102.........
SLSC10299......
H0103.........
SLSC10299......
H0104.........
SLSC10299......
$

Another way :

Code:

$ awk -v seq=S '
   seq=="H" && /^S/ { print; seq="S"; next }
   seq=="S" && /^H/ { print; seq="H"; next }
   ' lseq.txt
H0102.........
SLSC10299......
H0103.........
SLSC10299......
H0104.........
SLSC10299......
$

bufsn · #3 (**permalink**) 06-18-07, 09:32

Thanks a lot.

bufsn · #4 (**permalink**) 06-20-07, 11:53

H0102.........
SLSC10299......
H0103.........
H0104.........
SLSC10299......
H0105.........
SLSC10299......

In this case,
I want the following output

H0102.........
SLSC10299......
H0104.........
SLSC10299......
H0105.........
SLSC10299......

and not
H0102.........
SLSC10299......
H0103.........
SLSC10299......
H0105.........
SLSC10299......

aigles · #5 (**permalink**) 06-20-07, 13:49

Code:

$ awk '
   BEGIN { seq = "xx" }
   /^S/  { lineS = $0 }
   /^H/  { lineH = $0 }
   { seq = substr(seq, 2, 1) substr($0, 1, 1) }
   seq=="HS" { print lineH; print lineS }
   ' lseq.txt
H0102.........
SLSC10299......
H0104.........
SLSC10299......
H0104.........
SLSC10299......
$

bufsn · #6 (**permalink**) 06-20-07, 15:41

Perfect. Thanks.

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