Find a specific characters in a string

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Hello, I am trying to I get certain amino acids from my sequence, however, my output only gives that there are 3 of the amino acids I am looking for but I want it to tell me the amino acid name and create a new string.
I would also want my code to run other larger sequences if need be.
I am not sure if a swich case was the best approach to do this task. Can someone please help me, thank you!
aminoacids = 'MetArgGlyLeuAspTrpAspGlyAsn'
for d = 1:3:(length(aminoacids)-2)
rgroup = aminoacids(d:(d+2));
switch (rgroup)
case {'Arg', 'Asp', 'Cys', 'Glu','Lys','Tyr'}

Accepted Answer

Stephen23 on 25 Nov 2022
C = {'Arg', 'Asp', 'Cys', 'Glu','Lys','Tyr'};
T = 'MetArgGlyLeuAspTrpAspGlyAsn';
R = join(string(C),'|');
A = regexp(T,R,'match')
A = 1×3 cell array
{'Arg'} {'Asp'} {'Asp'}
Stephen23 on 26 Nov 2022
Edited: Stephen23 on 26 Nov 2022
"But this only works for cell type data? What if it is just a string?"
It works for string arrays too:
S = ["Arg", "Asp", "Cys", "Glu", "Lys", "Tyr"];
T = "MetArgGlyLeuAspTrpAspGlyAsn";
R = join(S,'|');
A = regexp(T,R,'match')
A = 1×3 string array
"Arg" "Asp" "Asp"

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More Answers (1)

Paul on 26 Nov 2022
Edited: Paul on 26 Nov 2022
Hi Miriam
I'm not quite sure what you're looking for. However, transforming everything to strings might offer a path forward via standard Matlab functions and indexing. For example
aminoacids = 'MetArgGlyLeuAspTrpAspGlyAsn';
C = string({'Arg', 'Asp', 'Cys', 'Glu','Lys','Tyr'})
S = string(reshape(aminoacids,3,[]).')
Find all the acids in S that are present in C
ans = 3×1 string array
"Arg" "Asp" "Asp"


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