How to search for strings in strings?

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Billy Jones
Billy Jones on 13 May 2020
Commented: Billy Jones on 13 May 2020
Hello,
I get many strings from our devices with some information. There are two different kinds of strings :
  1. 011_c_srr_Rtzfi_at000_hh5_fs_v343_l067_i1_Test_Test or 041_c_ddr_Rtzfi_ds000_hh5_fs_v343_l037_i1_Test_hall and so on ......
  2. 061_t_err_Rsas_au000_ti3_fs_v777_l011_ or 021_t_err_Rsas_au230_ti3_fs_v777_l031_ and so on ......
I need the following part of the string to get the information i need l067 / l037 / l011 and so on. l067 means 67% and I037 means 37%
So the result i want is 67 / 37 ..... :)
I am new here i spend several hours but my code does not work... :/
Thank you

Answers (3)

Antonio Jesús Periñan Freire
Hello,
you can do this easily with text processing.
First import the data
source = importdata('matlabtext.txt');
% Define a pattern (you can do this also for the other 2 patterns)
pattern = 'l067';
Then search for this pattern within the imported text file:
% This will return empty when the string pattern is not found:
rows_A = cellfun(@(x)strfind(x,pattern),source,'un',0);
% And convert that into ones and delete the empty values
rows_A = find(~cellfun(@isempty,rows_A));
Then simply get the length of the variable and this will give you the number of times that this string appears in the text:
num_A = length(rows_A)
  3 Comments
Billy Jones
Billy Jones on 13 May 2020
Is then your pattern _I0xx? or the _I0 string is repeated somewhere else? -> _I following with 3 three numbers is not repeating its unique ! Attention: _I100 means 100% after _I is not always 0! so i have to find _I and the the next 3 characters must be a number! Thx

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Walter Roberson
Walter Roberson on 13 May 2020
Edited: Walter Roberson on 13 May 2020
regexp(VARIABLE, '(?<=_l0)\d\d(?=_)', 'match', 'once')
VARIABLE can be a character vector, or a cell array of character vectors, or a string array.
You can str2double() the output

Stephen23
Stephen23 on 13 May 2020
Edited: Stephen23 on 13 May 2020
>> str = '011_c_srr_Rtzfi_at000_hh5_fs_v343_l067_i1_Test_Test';
>> tmp = regexp(str,'(?<=_l)\d+','match','once');
>> num = str2double(tmp)
num =
67
If multiple occurances then without 'once' option.

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