查找字符串中最短的重复模式 [英] Finding the shortest repetitive pattern in a string

问题描述

我想知道在Octave/matlab中是否可以进行模式匹配?我知道Maple 10有执行此操作的命令，但不确定在Octave/Matlab中我需要做什么.因此，如果数字为12341234123412341234，则模式匹配将为1234.我正在尝试找到最短的模式，该模式在重复时会生成整个字符串.

I was wondering if there was a way to do pattern matching in Octave / matlab? I know Maple 10 has commands to do this but not sure what I need to do in Octave / Matlab. So if a number was 12341234123412341234 the pattern match would be 1234. I'm trying to find the shortest pattern that upon repetiton generates the whole string.

请注意:数字(只会使用数字)不是那么简单.另外，我不会提前知道模式(这就是我要查找的东西).请参阅 枫叶10示例 在下面显示该模式不是预先知道的，但是命令会找到该模式.

Please note: the numbers (only numbers will be used) won't be this simple. Also, I won't know the pattern ahead of time (that's what I'm trying to find). Please see the Maple 10 example below which shows that the pattern isn't known ahead of time but the command finds the pattern.

Maple 10模式匹配示例:

Example of Maple 10 pattern matching:

ns:=convert(12341234123412341234,string);

             ns := "12341234123412341234"

StringTools:-PrimitiveRoot(ns);

             "1234"

如何在Octave/Matlab中执行此操作? 附:我正在使用Octave 3.8.1

How can I do this in Octave / Matlab? Ps: I'm using Octave 3.8.1

推荐答案

要查找重复生成整个字符串的最短模式，可以使用如下正则表达式:

To find the shortest pattern that upon repetition generates the whole string, you can use regular expressions as follows:

result = regexp(str, '^(.+?)(?=\1*$)', 'match');

一些例子:

>> str = '12341234123412341234';
>> result = regexp(str, '^(.+?)(?=\1*$)', 'match')
result = 
    '1234'

>> str = '1234123412341234123';
>> result = regexp(str, '^(.+?)(?=\1*$)', 'match')
result = 
    '1234123412341234123'

>> str = 'lullabylullaby';
>> result = regexp(str, '^(.+?)(?=\1*$)', 'match')
result = 
    'lullaby'

>> str = 'lullaby1lullaby2lullaby1lullaby2';
>> result = regexp(str, '^(.+?)(?=\1*$)', 'match')
result = 
    'lullaby1lullaby2'

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