Regex for removing repeating numbers on different lines [duplicate]

This question already has an answer here: 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 rem开发者_如何学运维ove 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

---

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.)

---

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

---

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

---

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!

---

Detecting such a pattern is not possible using regexp.

You can split the string by the "\n" and then compare.