Embedding a while into a for loop

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Maroulator
Maroulator 2016-8-5
评论： Maroulator 2016-8-6
I am trying to write a function which counts the amount of times a character pattern (p) can be found within another string; I am trying to use loops only. Below is the code that I have; I get no error, then again my code doesn't seem to execute. I think I am missing smth obvious and would appreciate a second pair of eyes; I have set dna='ATCCCGG' and p='CG'. Any input is welcome; many thanks in advance.
function [count] = countPattern_CM(dna,p)
%countPattern_CM This function finds out how many times a pattern p occurs
%in data
if length(p)>length(dna)
msgbox(['The pattern(p) that you entered is longer than the dna',...
'\nstring. Please enter new pattern(p)! ']);
else
count=0; %This variable captures the occurence of
%the pattern p within dna
for i=1:length(dna)
k=i+length(p)-1;
while k<=length(dna);
if strcmp(dna(1,i:k),p)==1;
count=count+1;
else
continue;
end
end
end
end
end
  1 个评论
Maroulator
Maroulator 2016-8-6
Stephen,
Thanks for the answer; you are correct, this is an academic exercise;)

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采纳的回答

Stephen23
Stephen23 2016-8-5
编辑：Stephen23 2016-8-5
You are turning something simple into something complicated. Just one loop is required:
dna = 'ATCCCGGCG';
p = 'CG';
%
Np = numel(p)-1;
count = 0;
for k = 1:numel(dna)-Np
count = count + strcmp(dna(k+(0:Np)),p);
end
However this task its a total waste of both your time and the computer's time: using inbuilt functions will be simpler, faster, and much more robust. Unless you have been given this as some academic exercise, there is no reason to try to reinvent the wheel by writing your own slower, buggier code. For example, this will always be faster and more reliable than anything you can write:
numel(strfind(dna,p))

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