Simplify a string with MATLAB script

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Lucas S 2020-2-27

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评论： Lucas S 2020-2-28

采纳的回答： Stephen23

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Hello !

I have a string format which looks like this (this is not always 'A' before '_' and numbers) :

Eq = 'A_1+((A_2+A_3)&(A_4+A_5))+A_6';

How can i simplify the string like this (with a script) :

Eq = 'A_(1+((2+3)&(4+5))+6)'

For me the simplest way would be to delete all 'A_' iteration except the first one and to add a '(' after the first 'A_' but i don't know how to do it in a script.

Thank you in advance for your help !

Edit : After Stephen answer review, i realized i missed a detail : sometimes the string can be like this :

'A_number_1+((A_number_2+A_number_3)&(A_number_+A_number_5))+A_number_6';
==> 'A_number_(1+((2+3)&(4+5))+6)'

With multiple string for example : 'String_String_String_1' . Is there anyway to delete string and '_' behind a number ?

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Answer 1

Stephen23 2020-2-27

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编辑：Stephen23 2020-2-27

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>> Eq = 'A_1+((A_2+A_3)&(A_4+A_5))+A_6';
>> Fq = regexprep(Eq, '^([A-Z]+_)(.*)', '$1\(${strrep($2,$1,'''')}\)')
Fq =
A_(1+((2+3)&(4+5))+6)

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Stephen23 2020-2-27

编辑：Stephen23 2020-2-28

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"Is there a way to delete all string before a '_' ?"

Of course, you just need to specify exactly what you require.

"Because with this script it only simplify 1st string which is 'A_' here"

Because that is exactly what you specified in your question.

So, making a few guesses... perhaps something like this does what you want (I added the missing '4'):

>> Eq = 'A_number_1+((A_number_2+A_number_3)&(A_number_4+A_number_5))+A_number_6';
>> Fq = regexprep(Eq, '^(\w+?)(\d+\W.*)', '$1\(${strrep($2,$1,'''')}\)')
Fq =
A_number_(1+((2+3)&(4+5))+6)

An example where I replaced "number" with some random digits:

>> Eq = 'A_123_1+((A_123_2+A_123_3)&(A_123_4+A_123_5))+A_123_6';
>> Fq = regexprep(Eq, '^(\w+?)(\d+\W.*)', '$1\(${strrep($2,$1,'''')}\)')
Fq =
A_123_(1+((2+3)&(4+5))+6)

And with the original example from your question:

>> Eq = 'A_1+((A_2+A_3)&(A_4+A_5))+A_6';
>> Fq = regexprep(Eq, '^(\w+?)(\d+\W.*)', '$1\(${strrep($2,$1,'''')}\)')
Fq =
A_(1+((2+3)&(4+5))+6)

How the regular expression is defined:

'^(\w+?)(\d+\W.*)'
%^                 match start of string
% (    )           token 1
%  \w+?            lazy match of letters, digits, and underscore
%       (       )  token 2
%        \d+       greedy match of digits
%           \W     match one non-letter, non-digit, non-underscore (e.g. plus, parenthesis, etc.)
%             .*   greedy match of any characters

Token 1 matches the 'String_String_String_' part of the name (or whatever you call it), but lazily (i.e. as few characters as possible), while token 2 greedily matches the digits, e.g. '1' (i.e. it tries to collect as many digits as possible). The \W forces the digits at the start of token 2 to be the last digit/s in the name (or whatever you call it), even if digits occur elsewhere in token 1. The replacement string works like this:

'$1\(${strrep($2,$1,'''')}\)'
%$1                            token 1, e.g. 'String_String_'
%  \(                     \)   literal parentheses
%    ${                  }     dynamic expression to call function
%      strrep($2,$1,'''')      all instances of token 1 in token 2 replaced with ''

Stephen23 2020-2-28

编辑：Stephen23 2020-2-28

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"'Or use regexp but for me regexp is only for same format's same length's string (i'm probably wrong)"

I can't see anything in the regular expression that restricts it to "same length's string" as you write, it adapts exaclty to the the length of the leading name, with any number of 'string_' repetitions.

When I run it on all of your example strings, I get the expected outputs, e.g.:

>> Eq = 'A_number_1+((A_number_2+A_number_3)&(A_number_4+A_number_5))+A_number_6';
>> Fq = regexprep(Eq, '^(\w+?)(\d+\W.*)', '$1\(${strrep($2,$1,'''')}\)')
Fq =
A_number_(1+((2+3)&(4+5))+6)

and

>> Eq = 'string_string_number_1+((string_string_number_2+string_string_number_3)&(string_string_number_4+string_string_number_5))+string_string_number_6';
>> Fq = regexprep(Eq, '^(\w+?)(\d+\W.*)', '$1\(${strrep($2,$1,'''')}\)')
Fq =
string_string_number_(1+((2+3)&(4+5))+6)

etc. etc.

Please show me a single example of my code that does not give the expected output, so that I can check it.

Lucas S 2020-2-28

Hmmm ok i'm dumb i tried with your 1st post thinking it was the new one ... My bad thank you !

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