replace character if repeated in line below
Clash Royale CLAN TAG#URR8PPP
I have the following sequence,
N
H
CB
CB
CG1
CG2
C
O
N
H
CB
CB
CG
CD
.
.
.
and I would like to replace the first "CB" with "CA" when "CB" is repeated in line below, so as to end up with the following sequence
N
H
CA
CB
CG1
CG2
C
O
N
H
CA
CB
CG
CD
.
.
.
text-processing awk sed
edited Feb 28 at 16:28
Jeff Schaller♦
44k1161142
asked Feb 28 at 16:08
Dimitris MintisDimitris Mintis
805
add a comment |
I have the following sequence,
N
H
CB
CB
CG1
CG2
C
O
N
H
CB
CB
CG
CD
.
.
.
and I would like to replace the first "CB" with "CA" when "CB" is repeated in line below, so as to end up with the following sequence
N
H
CA
CB
CG1
CG2
C
O
N
H
CA
CB
CG
CD
.
.
.
text-processing awk sed
edited Feb 28 at 16:28
Jeff Schaller♦
44k1161142
asked Feb 28 at 16:08
Dimitris MintisDimitris Mintis
805
If you were after the general case ("when the next line == the current line, decrement the current line") then be aware that the "what is predecessor of a string" is tricky. For example, what is the predecessor of "CG1"? Is is "CG0" or "CG" or something else?
– glenn jackman
Feb 28 at 17:50
sed -E '$!N;s/^(CB)(n1)$/CA2/'
– Rakesh Sharma
Mar 1 at 0:50
add a comment |
I have the following sequence,
N
H
CB
CB
CG1
CG2
C
O
N
H
CB
CB
CG
CD
.
.
.
and I would like to replace the first "CB" with "CA" when "CB" is repeated in line below, so as to end up with the following sequence
N
H
CA
CB
CG1
CG2
C
O
N
H
CA
CB
CG
CD
.
.
.
text-processing awk sed
edited Feb 28 at 16:28
Jeff Schaller♦
44k1161142
asked Feb 28 at 16:08
Dimitris MintisDimitris Mintis
805
I have the following sequence,
N
H
CB
CB
CG1
CG2
C
O
N
H
CB
CB
CG
CD
.
.
.
and I would like to replace the first "CB" with "CA" when "CB" is repeated in line below, so as to end up with the following sequence
N
H
CA
CB
CG1
CG2
C
O
N
H
CA
CB
CG
CD
.
.
.
text-processing awk sed
text-processing awk sed
edited Feb 28 at 16:28
Jeff Schaller♦
44k1161142
asked Feb 28 at 16:08
Dimitris MintisDimitris Mintis
805
edited Feb 28 at 16:28
Jeff Schaller♦
44k1161142
asked Feb 28 at 16:08
Dimitris MintisDimitris Mintis
805
edited Feb 28 at 16:28
Jeff Schaller♦
44k1161142
edited Feb 28 at 16:28
Jeff Schaller♦
44k1161142
edited Feb 28 at 16:28
Jeff Schaller♦
44k1161142
44k1161142
asked Feb 28 at 16:08
Dimitris MintisDimitris Mintis
805
asked Feb 28 at 16:08
Dimitris MintisDimitris Mintis
805
asked Feb 28 at 16:08
Dimitris MintisDimitris Mintis
805
805
If you were after the general case ("when the next line == the current line, decrement the current line") then be aware that the "what is predecessor of a string" is tricky. For example, what is the predecessor of "CG1"? Is is "CG0" or "CG" or something else?
– glenn jackman
Feb 28 at 17:50
sed -E '$!N;s/^(CB)(n1)$/CA2/'
– Rakesh Sharma
Mar 1 at 0:50
add a comment |
If you were after the general case ("when the next line == the current line, decrement the current line") then be aware that the "what is predecessor of a string" is tricky. For example, what is the predecessor of "CG1"? Is is "CG0" or "CG" or something else?
– glenn jackman
Feb 28 at 17:50
sed -E '$!N;s/^(CB)(n1)$/CA2/'
– Rakesh Sharma
Mar 1 at 0:50
If you were after the general case ("when the next line == the current line, decrement the current line") then be aware that the "what is predecessor of a string" is tricky. For example, what is the predecessor of "CG1"? Is is "CG0" or "CG" or something else?
– glenn jackman
Feb 28 at 17:50
If you were after the general case ("when the next line == the current line, decrement the current line") then be aware that the "what is predecessor of a string" is tricky. For example, what is the predecessor of "CG1"? Is is "CG0" or "CG" or something else?
– glenn jackman
Feb 28 at 17:50
sed -E '$!N;s/^(CB)(n1)$/CA2/' – Rakesh Sharma
Mar 1 at 0:50
sed -E '$!N;s/^(CB)(n1)$/CA2/' – Rakesh Sharma
Mar 1 at 0:50
add a comment |
1 Answer
1
active
oldest
votes
This sort of thing is a lot simpler to wrap your head around if you can read the file backwards. Fortunately, tac (which is cat backwards because that's what it does) is there to let us do this. We can then make a note when we see a "CB", and if we see "CB" on the next (formerly previous) line, edit it; then flip it back-to-front again with another use of tac:
$ tac input | awk '/CB/ && found==1 $1="CA"; found=0 /CB/ && found==0 found=1 ! /CB/ && found==1 found=0 print' | tac
N
H
CA
CB
CG1
CG2
C
O
N
H
CA
CB
CG
CD
answered Feb 28 at 16:22
DopeGhotiDopeGhoti
46.6k56190
many thanks!! works fine!!
– Dimitris Mintis
Feb 28 at 16:29
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
This sort of thing is a lot simpler to wrap your head around if you can read the file backwards. Fortunately, tac (which is cat backwards because that's what it does) is there to let us do this. We can then make a note when we see a "CB", and if we see "CB" on the next (formerly previous) line, edit it; then flip it back-to-front again with another use of tac:
$ tac input | awk '/CB/ && found==1 $1="CA"; found=0 /CB/ && found==0 found=1 ! /CB/ && found==1 found=0 print' | tac
N
H
CA
CB
CG1
CG2
C
O
N
H
CA
CB
CG
CD
answered Feb 28 at 16:22
DopeGhotiDopeGhoti
46.6k56190
many thanks!! works fine!!
– Dimitris Mintis
Feb 28 at 16:29
add a comment |
This sort of thing is a lot simpler to wrap your head around if you can read the file backwards. Fortunately, tac (which is cat backwards because that's what it does) is there to let us do this. We can then make a note when we see a "CB", and if we see "CB" on the next (formerly previous) line, edit it; then flip it back-to-front again with another use of tac:
$ tac input | awk '/CB/ && found==1 $1="CA"; found=0 /CB/ && found==0 found=1 ! /CB/ && found==1 found=0 print' | tac
N
H
CA
CB
CG1
CG2
C
O
N
H
CA
CB
CG
CD
answered Feb 28 at 16:22
DopeGhotiDopeGhoti
46.6k56190
many thanks!! works fine!!
– Dimitris Mintis
Feb 28 at 16:29
add a comment |
This sort of thing is a lot simpler to wrap your head around if you can read the file backwards. Fortunately, tac (which is cat backwards because that's what it does) is there to let us do this. We can then make a note when we see a "CB", and if we see "CB" on the next (formerly previous) line, edit it; then flip it back-to-front again with another use of tac:
$ tac input | awk '/CB/ && found==1 $1="CA"; found=0 /CB/ && found==0 found=1 ! /CB/ && found==1 found=0 print' | tac
N
H
CA
CB
CG1
CG2
C
O
N
H
CA
CB
CG
CD
answered Feb 28 at 16:22
DopeGhotiDopeGhoti
46.6k56190
This sort of thing is a lot simpler to wrap your head around if you can read the file backwards. Fortunately, tac (which is cat backwards because that's what it does) is there to let us do this. We can then make a note when we see a "CB", and if we see "CB" on the next (formerly previous) line, edit it; then flip it back-to-front again with another use of tac:
$ tac input | awk '/CB/ && found==1 $1="CA"; found=0 /CB/ && found==0 found=1 ! /CB/ && found==1 found=0 print' | tac
N
H
CA
CB
CG1
CG2
C
O
N
H
CA
CB
CG
CD
answered Feb 28 at 16:22
DopeGhotiDopeGhoti
46.6k56190
answered Feb 28 at 16:22
DopeGhotiDopeGhoti
46.6k56190
answered Feb 28 at 16:22
DopeGhotiDopeGhoti
46.6k56190
answered Feb 28 at 16:22
DopeGhotiDopeGhoti
46.6k56190
46.6k56190
many thanks!! works fine!!
– Dimitris Mintis
Feb 28 at 16:29
add a comment |
many thanks!! works fine!!
– Dimitris Mintis
Feb 28 at 16:29
many thanks!! works fine!!
– Dimitris Mintis
Feb 28 at 16:29
many thanks!! works fine!!
– Dimitris Mintis
Feb 28 at 16:29
add a comment |
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If you were after the general case ("when the next line == the current line, decrement the current line") then be aware that the "what is predecessor of a string" is tricky. For example, what is the predecessor of "CG1"? Is is "CG0" or "CG" or something else?
– glenn jackman
Feb 28 at 17:50
sed -E '$!N;s/^(CB)(n1)$/CA2/'– Rakesh Sharma
Mar 1 at 0:50