What changes are needed in the code?

i want to swaps characters of s as specified by the indices present in the pairs variable. pairs is a 2-column matrix, where on each row, i have given the positions of the two characters that need to swap. eg s = orange & pairs = [1 2]. out expected is roange. what changes you recommend in this code.

function [arr] = shuffletext ( pairs, s)

a = 0;
b = 0;
for i = 1:numel(s)
	for j = pairs 
		s(i) = a;
		a = b;
		b = s(i);
	end 
end
arr = b; 

Still its not showing any output just a blank if i call the function

using: disp( shuffletext( [1 2], 'orange') )

Output

>> disp( shuffletext( [1 2], 'orange') )
 
>> 

[Cris LaPierre]

Also asked here:

https://www.mathworks.com/matlabcentral/answers/1584369-how-can-we-use-for-loop-to-get-index-of-matrix-and-letters?s_tid=srchtitle

Answer 1

[Cris LaPierre]

See this answer.

p = [1 2];
s = 'orange';
s(p) = s(fliplr(p))

s = 'roange'

[Manav Divekar]

I know this function but want to see if for loop also works or not, you can help me with for loop that would be great.

[Cris LaPierre]

If you know the indices, I don't see why you need for loops.

[Manav Divekar]

if there is a matrix like [1 2; 4 2] then output expected for orange in first row is roange and the for second row will be rnaoge, the itreration is required. Thats the reason i there is need of for loop.

[Cris LaPierre]

That explains the outer loop, but not the inner one.

There is no 'swap' feature. You need to

1. copy the first letter to a temporary variable
2. replace the first letter in s with the second letter
3. Replace the second letter in s with the letter dopied in step 1

[Manav Divekar]

function [arr] = shuffletext ( pairs, s)
a = 0;
b = 0;
for i = 1:numel(s)
	for j = pairs 
		s(i) = a;
		a = b;
		b = s(i);
	end 
end
arr = b; 

Still its not showing any output just a blank if i call the function

using: disp( shuffletext( [1 2], 'orange') )

Output

>> disp( shuffletext( [1 2], 'orange') )
 
>> 

[Cris LaPierre]

I strongly recommend going through MATLAB Onramp. It will help give you an good understanding of the fundamentals of MATLAB.

Again, do don't need the second for loop because you are not using j anywhere.

Also, assignment (equals sign) places what is on the right into what is on the left. So s(i) = a will take the value assigned to a, which is 0, and place it in the ith position of s. This assignment is likely not doing what you expect since s is a character array and a is a double.

a=0;
s='orange';
s(2) = a

s = 'o ange'