how to find strings of varying length within longer strings

Question

NB 2015-7-8

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评论： NB 2015-7-9

I have a cell array where the first row of each column is a long string that always starts with "HA", then a number, and then more text.

For example:

HA2.hdhashasdh HA33.dskljdasjkdajkls HA80.djklasjdjklads HA81.djkhadsh HA245.fsaldjajdalsj

Then I have a vector with some of the numbers that come after 'HA'

list = [2, 81, 245]

I want to make a loop that for each string of my cell array, finds whether it starts with 'HA[one of the numbers in my list]', and returns 1 if it does and 0 if it doesn't.

I've tried to use strncmp, but there were some problems.

This is the loop I was using:

counter = 1
for i=1:length(myArray(1, :))
    question = myArray(1, i); %the string I'm currently looking at
    num = list(counter); %the question number
    name = strcat('HA', num2str(num)); %the name of the question (e.g. HA42)
    if strncmp(name, question, 4) == 1
        question
        name
        counter = counter +1;
    end
end

The problem is that 'name' is not always the same length, since the numbers in my list are 2, 80 and 245. So if I do strncmp(name, question, 4) or strncmp(name, question, 5), it always returns 0, but if I do strncmp(name, question, 3) it can return 1 even though it's wrong: for example if name is HA81, it will return 1 once it's on question HA80.jdfdskljf.

I wanted to know if there is another function to do this or any way I could make it work. Let me know if anything wasn't clear (I'm still newish to Matlab) Thanks!

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Answer 1

Azzi Abdelmalek 2015-7-8

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https://ww2.mathworks.cn/matlabcentral/answers/229091-how-to-find-strings-of-varying-length-within-longer-strings#answer_185460

编辑：Azzi Abdelmalek 2015-7-8

str={'HA2.hdhashasdh'   'HA33.dskljdasjkdajkls'  'hh'  'HA80.djklasjdjklads'  'HA81.djkhadsh'  'HA245.fsaldjajdalsj' 'er'}
list=[2,81,245]
n=regexp(str,'(?<=HA)\d+\>','match','once')
id=str2double(n)
out=ismember(id,list)

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NB 2015-7-9

that looks great, thanks! I'll see if I can apply it to my real data.

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Answer 2

Alex 2015-7-8

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https://ww2.mathworks.cn/matlabcentral/answers/229091-how-to-find-strings-of-varying-length-within-longer-strings#answer_185489

Try strfind.

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NB 2015-7-9

strfind doesn't do what I want it to do: I want something that like strcmp gives me a 1 if it finds the string and a 0 if it doesn't. It seems like there should be a way to use strncmp (which compares not the entire string but just a certain number of characters) but with varying numbers of characters (e.g. from 3 to 5 characters). Or do you think maybe there is a way to use strfind to do this?

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