Find substring with certain pattern anywhere in a string

Question

I got many strings from our device (array). There are two different kinds of strings :

011_c_srr_Rtzfi_at000_hh5_fs_v343_l067_i1_Test_Test
041_c_ddr_Rtzfi_ds000_hh5_fs_v343_l037_i1_Test_hall (the needed information is in the middle of the string)
061_t_err_Rsas_au000_ti3_fs_v777_l011_ *
021_t_err_Rsas_au230_ti3_fs_v777_l031_ (the needed information is at the end of the string)

Conclusion: I need the following part of the string l067 / l037 / l011 ..... For example l067 means 67% and I037 means 37%. So i need this two percent values. The result is 67 and 37. My Code: (only parts)

for j=1:numRows;
Name=LaSP.Messung(j, 1).name
Size=size(Name)
Length = strlength(Name)%Evaluiert die Länge des gesamten Strings
pos1 = findstr(Name, '_')%Listet alle "_" im String auf
[zeile1,spalte1]=size(pos1)
spalte=pos1(1,spalte1)%ich hol mir string position vom letzten "_"

if spalte==Length%Abfrage ob das letzte zeichen ist ein "_"
%%Abfrage ob der Wert schon einmal vorkam   
    %%die letzten 4 auslesen
else 
    %%in mitten des strings
end

      %pos = strfind(Name, '_')
 %k = strfind(Name,'_','ForceCellOutput',true)
 %idx = find(strcmp(Name, '_'))
 %pat='_';
%ind=regexp(Name,pat);
% word_to_find=strfind(strarray,'stringtofind');
% starray.index(word_to_find);
end

My problem is i can not split the string ... i can not extract the last 4 characters... Thank you

Thanks for posting your desired input & output and code, but what is the problem with the code? Were are you stuck? (Sidenote: whilst not disallowed on SO, having your in-code comments in German makes it more difficult to understand for non-German speakers). I'd do a strplit() on the dash, _, and then grab the ninth cell. — Adriaan
– Adriaan, Commented May 13, 2020 at 9:17

Paolo · Accepted Answer · 2020-05-13 10:55:59Z

1

Given:

my_strings = {'011_c_srr_Rtzfi_at000_hh5_fs_v343_l067_i1_Test_Test',
'041_c_ddr_Rtzfi_ds000_hh5_fs_v343_l037_i1_Test_hall',
'061_t_err_Rsas_au000_ti3_fs_v777_l011_ *',
'021_t_err_Rsas_au230_ti3_fs_v777_l031_'};

few possible solutions here.

Using regex to match, we can build our pattern to look for the characters after v followed by three digits and underscore (e.g. v777_)

matches = regexp(my_strings,'v\d{3}_([^_]+)','tokens','once');
[matches{:}]
ans =

  1×4 cell array

  {'l067'}    {'l037'}    {'l011'}    {'l031'}

Using regex to split on underscore, and then taking the 9th cell:

split_strings = regexp(my_strings,'_','split');
matches = cellfun(@(x) x(9),split_strings).'
ans =

 1×4 cell array

 {'l067'}    {'l037'}    {'l011'}    {'l031'}

Using strsplit to split on underscore, and then taking the 9th cell:

n = numel(my_strings);
matches = char.empty(0,n);
for i = 1:n
  split_string = strsplit(my_strings{i},'_');
  matches = [matches split_string(9)];
end
matches =

  1×4 cell array

  {'l067'}    {'l037'}    {'l011'}    {'l031'}

edited May 13, 2020 at 10:55

answered May 13, 2020 at 10:42

Paolo

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2 Comments

Franz H Over a year ago

Hello one question again... What shall i do if it is not the 9th cell?

Paolo Over a year ago

@FranzH Which cell is it? Just 9 to that number

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