Best solution to finding repeating characters on a line.

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I am looking for any instances of two characters (e/d) being repeated in a row greater then or equal to 10. I just want to either print every line that this occurs to the command line or stop and print the location of the stop everytime it is detected. Basically I am trying to find when e and d show up over ten times grouped together in a large data file. For example:
asdfsdfsdfsasdfsdfsdfsasdfsdfsdfs
asseefadfefeeedddeeedddasdfsdf
asdfsdfsdfsasdfsdfsdfsasdfsdfsdfs
asseefadfefeeedddeeedddasdfsdf
The script would then print out line 2 and line 4 in the command line.
Thank you for your help

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Stephen23
Stephen23 il 13 Lug 2021
Modificato: Stephen23 il 13 Lug 2021
inp = {'asdfsdfsdfsasdfsdfsdfsasdfsdfsdfs';'asseefadfefaaadddaaadddasdfsdf';'asdfsdfsdfsasdfsdfsdfsasdfsdfsdfs';'asseefadfefaaadddaaadddasdfsdf'};
rgx = '(.)(??$1*)(.?)(??[$1$2]*)';
spl = regexp(inp,rgx,'match');
idx = cellfun(@(c)any(cellfun(@numel,c)>9),spl);
find(idx)
ans = 2×1
2 4
  5 Commenti
Walter Roberson
Walter Roberson il 13 Lug 2021
The bold text does not represent repetitions this time, not unless you mean repetition between lines. In the previous example there was two halves, with the second being the same as the first.
If the task is to find places where there is a string of at least 10 d or e characters then
'[de]{10,}'
can find that, and the 'once' and isempty and indexing from my Answer gives you the rest. It just depends on your having used readlines() on the file.
Stephen23
Stephen23 il 13 Lug 2021
Modificato: Rena Berman il 22 Set 2023
Matthew Worker: are the specific characters known in advance? Or do you want to detect them automatically? (i.e. detect any two characters that are repeated more than 10 times contiguously)
Are there any particular patterns that you need to include/exclude? (e.g. does 10 'e' characters in a row count, or does the sequence have to include at least one 'd' character?).

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Più risposte (1)

Walter Roberson
Walter Roberson il 13 Lug 2021
You say "10 or over", so is it correct that the program needs to all possible patterns? For example,
'adadadadaaaadadadadaaa'
ans = 'adadadadaaaadadadadaaa'
(length 22) should be located if it exists?
S = {'asseefadfefaaadddaaadddasdfsdf', 'asseeadadadadaaaadadadadaaadfsdf'}
S = 1×2 cell array
{'asseefadfefaaadddaaadddasdfsdf'} {'asseeadadadadaaaadadadadaaadfsdf'}
matches = regexp(S, '([ad]{5,})\1', 'match');
celldisp(matches)
matches{1}{1} = aaadddaaaddd matches{2}{1} = adadadadaaaadadadadaaa
  5 Commenti
Matthew Worker
Matthew Worker il 13 Lug 2021
@Walter Roberson Two specific characters (d/e), sorry should've gone more in depth. The problem is already solved as I can convert the data to an array. But if you know a way of going through a block of text data (in a txt file) and stating the lines it is detected, I would be very appreciative.
Thank you for you previous answer as it does give a good explanation.
Walter Roberson
Walter Roberson il 14 Lug 2021
Example of reading from file:
%create a file for demonstration purposes only
tname = [tempname() '.txt'];
fid = fopen(tname, 'w');
T = regexprep('asseefadfefaaadddaaadddasdfsdf\nasseeadadadadaaaadadadadaaadfsdf\nasdfsdfsdfsasdfsdfsdfsasdfsdfsdfs\nasseefadfefaaadddaaadddasdfsdf\nasdfsdfsdfsasdfsdfsdfsasdfsdfsdfs\nasseefadfefaaadddaaadddasdfsdf\n', 'a', 'e');
fprintf(fid, T);
fclose(fid);
%okay, main function
filename = tname;
%okay, main function
S = readlines(filename);
matches = S(~cellfun(@isempty, regexp(S, '[de]{10}', 'once')));
matches
matches = 4×1 string array
"esseefedfefeeedddeeedddesdfsdf" "esseeededededeeeededededeeedfsdf" "esseefedfefeeedddeeedddesdfsdf" "esseefedfefeeedddeeedddesdfsdf"
%alternative without readlines
S = regexp(fileread(filename), '\r?\n', 'split');
matches = S(~cellfun(@isempty, regexp(S, '[de]{10}', 'once')));
matches
matches = 1×4 cell array
{'esseefedfefeeedddeeedddesdfsdf'} {'esseeededededeeeededededeeedfsdf'} {'esseefedfefeeedddeeedddesdfsdf'} {'esseefedfefeeedddeeedddesdfsdf'}
%alternative without splitting
S = fileread(filename);
matches = regexp(S, '^.*[de]{10}.*$', 'match', 'dotexceptnewline', 'lineanchors');
matches
matches = 1×4 cell array
{'esseefedfefeeedddeeedddesdfsdf'} {'esseeededededeeeededededeeedfsdf'} {'esseefedfefeeedddeeedddesdfsdf'} {'esseefedfefeeedddeeedddesdfsdf'}

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