Regex for removing repeating numbers on different lines [duplicate] - regex

Question

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Reference - What does this regex mean?
(1 answer)
Closed 3 years ago.
It's perhaps quite simple, but I can't figure it out:
I have a random number (can be 1,2,3 or 4 digits)
It's repeating on a second line:
2131
2131
How can I remove the first number?
EDIT: Sorry I didn't explained it better. These lines are in a plain text file. I'm using BBEdit as my editor. And the actual file looks like this (only then app. 10.000 lines):
336
336
rinde
337
337
diving
338
338
graffiti
339
339
forest
340
340
mountain
If possible the result should look like this:
336 - rinde
337 - diving
338 - graffiti
339 - forest
340 - mountain

Answer 1

Search:
^(\d{1,4})\n(?:\1\n)+([a-z]+$)
Replace:
\1 - \2
I don't have access to BBEdit, but apparently you have to check the "Grep" option to enable regex search-n-replace. (I don't know why they call it that, since it seems to be powered by the PCRE library, which is much more powerful than grep.)

Answer 2

since you didn't mention any programming language, tools. I assume those numbers are in a file. each per line, and any repeated numbers are in neighbour lines. uniq command can solve your problem:
kent$ echo "1234
dquote> 1234
dquote> 431
dquote> 431
dquote> 222
dquote> 222
dquote> 234"|uniq
1234
431
222
234

Answer 3

Another way find: /^(\d{1,4})\n(?=\1$)/ replace: ""
modifiers mg (multi-line and global)
$str =
'1234
1234
431
431
222
222
222
234
234';
$str =~ s/^(\d{1,4})\n(?=\1$)//mg;
print $str;
Output:
1234
431
222
234
Added On the revised sample, you could do something like this:
Find: /(?=^(\d{1,4}))(?:\1\n)+\s*([^\n\d]*$)/
Replace: $1 - $2
Mods: /mg (multi-line, global)
Test:
$str =
'
336
336
rinde
337
337
337
diving
338
338
graffiti
339
337
339
forest
340
340
mountain
';
$str =~ s/(?=^(\d{1,4}))(?:\1\n)+\s*([^\n\d]*$)/$1 - $2/mg;
print $str;
Output:
336 - rinde
337 - diving
338 - graffiti
339
337
339 - forest
340 - mountain
Added2 - I was more impressed with the OP's later desired output format than the original question. It has many elements to it so, unable to control myself, generated a way too complicated regex.
Search: /^(\d{1,4})\n+(?:\1\n+)*\s*(?:((?:(?:\w|[^\S\n])*[a-zA-Z](?:\w|[^\S\n])*))\s*(?:\n|$)|)/
Replace: $1 - $2\n
Modifiers: mg (multi-line, global)
Expanded-
# Find:
s{ # Find a single unique digit pattern on a line (group 1)
^(\d{1,4})\n+ # Grp 1, capture a digit sequence
(?:\1\n+)* # Optionally consume the sequence many times,
\s* # and whitespaces (cleanup)
# Get the next word (group 2)
(?:
# Either find a valid word
( # Grp2
(?:
(?:\w|[^\S\n])* # Optional \w or non-newline whitespaces
[a-zA-Z] # with at least one alpha character
(?:\w|[^\S\n])*
)
)
\s* # Consume whitespaces (cleanup),
(?:\n|$) # a newline
# or, end of string
|
# OR, dont find anything (clears group 2)
)
}
# Replace (rewrite the new block)
{$1 - $2\n}xmg; # modifiers expanded, multi-line, global

Answer 4

find:
((\d{1,4})\r(\D{1,10}))|(\d{1,6})
replace:
\2 - \3
You should be able to clean it up from there quite easily!

Answer 5

Detecting such a pattern is not possible using regexp.
You can split the string by the "\n" and then compare.