Lua pattern to match similar consecutive digits

Asked Jul 20 '15 at 22:38

Active Jul 22 '15 at 12:31

Viewed 537 times

I have a string that contains only digits from 2 to 9, like '223488875662264442', it is guaranteed that it does not contain more than 3 adjacent similar digits, for example, it cannot contain '7777', but it can contain '27747772'.

I want to make a pattern that matches all the similar consecutive numbers, example:

    > str = '44788895532244474568884511123331566';
    > for n in string.gmatch(str,pat) do -- pat is the pattern
    >>    print(n);
    > end
    44
    7
    888
    9
    55
    ...

tried with patterns like '(%d)%1*' with no success.

I cannot use regex,I need to do it with Lua patterns.

edited Jul 22 '15 at 12:31

asked Jul 20 '15 at 22:38

Redouane Red

possible duplicate of [Regex to find repeating numbers](http://stackoverflow.com/questions/6507982/regex-to-find-repeating-numbers) – Rossiar Jul 20 '15 at 22:47
You'll want to use `(\d)\1+` like in http://stackoverflow.com/questions/6507982/regex-to-find-repeating-numbers – Rossiar Jul 20 '15 at 22:47
2

@Rossiar it's not a dupe since the OP is using Lua patterns and not regex, the solution won't work here so I've updated the question to remove mentions of regex. – ryanpattison Jul 21 '15 at 00:02
3

`for n in str:gsub('.','%0%0\0'):gsub('(.)%z%1','%1'):gmatch'.(.-)%z' do` – Egor Skriptunoff Jul 21 '15 at 02:15
@EgorSkriptunoff What does '%0%0\0' mean? – Redouane Red Jul 22 '15 at 12:27
1

@RedouaneRed - It means "repeat captured character twice and append \0" – Egor Skriptunoff Jul 22 '15 at 12:52

Lua pattern to match similar consecutive digits

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