Function, in MATLAB dna replication - matlab

Question

I'm trying to figure out the function command in Matlab and im having some difficulties.
I'm trying to write a Matlab function named dna_replicate. It will replicate a given strand and return its partner strand
For example if the user enters ATGCATGCAHGCAGTC, it should return TACGTACGT CGTCAG
A-->T
G-->C if the user enters other than these 4 letters, there should be blank in the partner strand. Thank you for your help

Answer 1

This implementation should be faster, involving only a simple table look-up. Note that the table t is constructed only once when the function is first called.
function out = dna_replicate(in)
persistent t
if isempty(t)
t = blanks(256);
t('ATGC') = 'TACG';
end
out = t(in);
end

Answer 2

How about:
function out = dna_replicate(in)
in = upper(in); % Ensures all same case
A = in=='A';
T = in=='T';
C = in=='C';
G = in=='G';
out = in;
out(A) = 'T';
out(T) = 'A';
out(C) = 'G';
out(G) = 'C';
out(~(A|T|C|G)) = ' ';
while #Jirka cigler answer works, it uses a for loop as well as dynamically growing vector 'out'. As matlab is optimized for vector operations, this answer should perform better.

Answer 3

You can create a simple vectorized solution using the function ISMEMBER:
function outString = dna_replicate(inString)
[~,index] = ismember(upper(inString),'ACGT'); %# Find the indices of inStrings
%# letters in string `ACGT`
outString = 'ACGT '; %# Initialize outString to `ACGT` and a blank
outString = outString(5-index); %# Use inverted and shifted index to expand
%# outString to the size of inString
end
And here's a test:
>> dna_replicate('ATGCATGCAHGCAGTC')
ans =
TACGTACGT CGTCAG

Answer 4

I think it can be implemented as follows:
function out=dna_replicate(in)
for i=1:numel(in)
switch in(i)
case 'A'
out(i)= 'T';
case 'G'
out(i)= 'C';
case 'T'
out(i)='A';
case 'C'
out(i)='G';
otherwise
out(i)=' ';
end
end
this function has argument of type char
in='ATGCATGCAHGCAGTC'
and you can run
out=dna_replicate(in)
to get the same result as you want :-)