使用circshift octave / matlab进行数组操作

Question

1) I'm trying to shift an array's (outer cells) first and last cell inward at the same time. Here's an inward animation of what I'm trying to do with the array inward animation . As you can see the outer cells are moving inward (from the ends) at the same time

Here's a pic but the animation shows it much better please note the array could have either an even or odd amount of cells

Inner rotation steps
1 2 3 4 5 6 7
4 1 2 3 6 7 5
3 4 1 2 7 5 6

2) I'm trying to shift an array's middle cells outward using circshift (which I think is fastest) at the same time. Here's an outward animation of what I'm trying to do also outward animation . As you can see the middle of the signal is moving outward (left and right) at the same time.

Here's a pic but the animation shows it much better please note the array could have either an even or odd amount of cells

Outer rotation steps
1 2 3 4 5 6 7
2 3 4 1 7 5 6
3 4 1 2 6 5 7

Example: inward
a = (1:7)
y=circshift(A,[0 -2]) %shift end of array inward
3   4   5   6   7   1   2

a = (1:7)
y=circshift(A,[0 2]) %shift beginning of array inward
6   7   1   2   3   4   5

Not to sure how to do the middle cells shifting outward using circshift or the outer cells shifting inward at the same time

I'm not sure about how to start circshift from the center and move the array outwards / inwards to get this effect.

Please note I'm not trying to get this equation I'm just trying to get the arrays to move in the same way. I'm using octave 3.8.1 which is compatible with matlab.

Answer 1

A = 1:7;

split = ceil(numel(A)/2);

n = 2;
A(1:split) = circshift(A(1:split), [0, n]);
A(split+1:end) = circshift(A(split+1:end), [0, -n]);

Put the last three lines in a loop if you like. Also just change the signs of n for inwards or outwards

Answer 2

what about constructing new indices instead of using circshift:

A = 1:7;

halfLen = ceil(length(A)/2); % or use ceil to 
idcsOutward = [2:halfLen,1,length(A),(halfLen+1):(length(A)-1)];

B1 = A(idcsOutward)
B2 = B1(idcsOutward)

% and inward:
idcsInward = [halfLen,1:(halfLen-1),(halfLen+2):length(A),halfLen+1];

C1 = A(idcsInward)
C2 = C1(idcsInward)

Result is:

B1 =
     2     3     4     1     7     5     6

B2 =
     3     4     1     2     6     7     5

C1 =
     4     1     2     3     6     7     5

C2 =
     3     4     1     2     7     5     6