How to move an element from an array?

I have an array and i want to to move the element a which located in x line, by one position to the right without change the left part

[Guillaume]

Can you provide an example of before and after?

[GEORGIOS KOULIDIS]

I have the array

A=[ 1 2 3 4 0 0 0;
    5 3 2 1 0 0 0]

and i want to do that

A=[ 1 2 3 4 0 0 0;
    5 3 0 2 1 0 0]

[Pal Szabo]

If you have this as original array:

 A=[ 1 2 3 4 0 0 0;
     5 3 2 1 0 0 0;
     4 4 4 4 0 0 0;
     2 3 4 5 6 7 8]

You want to move the elements starting from line row=2, column=3 (this is your number two), and replace the element originally in position row=2 column=3 by another element stored in the variable replacewith (in this case 0), then write:

 A=[ 1 2 3 4 0 0 0;
    5 3 2 1 0 0 0;
    4 4 4 4 0 0 0;
    2 3 4 5 6 7 8]

 x=2
 y=3
 replacewith=0;

 result_xth_row=[A(x,1:y-1),replacewith,A(x,y:end-1)]

 A(x,1:end)=result_xth_row

 A

Answer 1

[Cam Salzberger]

Hello Georgios,

I'm not sure what the absolute best way to do this for your particular application, but here is one way you could do it.

A = [1 2 3 4 0 0 0 ; 5 3 2 1 0 0 0];
Aorig = A;
A(2,4:5) = Aorig(2,3:4);
A(2,3) = Aorig(2,5);

Or if you'd rather one-line it:

A(2,3:5) = A(2,[5 3 4]);

I'll let you work out a more general function though, depending on what you know, and what you'll need to adapt for as an input.

-Cam

[GEORGIOS KOULIDIS]

can you give me a general answer please ?

[Cam Salzberger]

Like I said, I don't know why you are trying to do this, so I don't know what the general case is. If you are always going to be moving two values on the second row of the matrix to one earlier position, it could be as simple as:

function A = shiftTwoVals(A,iCol)
    A(2,[iCol-1:iCol+1]) = A(2,[iCol+1 iCol-1 iCol]);
end

If you just want a general case of swapping any elements with any other elements in the matrix, then you are better off learning what I did with the indexing, since that is the best way. On the left side of the equals sign, the indices of the matrix tell it which positions are going to be modified. On the right side of the equals sign, the indices of the matrix tell it which values to use.

It can be simpler to visualize if you index linearly rather than with row and column values.

Answer 2

[Andrei Bobrov]

A(2,3:end) = circshift(A(2,3:end),1)

[GEORGIOS KOULIDIS]

it doesnot run It show me this message : Warning: CIRCSHIFT(X,K) with scalar K and where size(X,1)==1 will change behavior in future versions. To retain current behavior, use CIRCSHIFT(X,[K,0]) instead.