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How can I shift the elements in a vector without losing the elements? just shift the order

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Nurahmed
Nurahmed on 23 Jun 2019
Answered: Nurahmed on 24 Jun 2019
If I have
A = [1,2,3,4,5,6,7,8,9,10];
I want specific consecutive number of elements (e.g. 6,7,8) to shift left or shift right n bits. Assume I know the number orders and elements in the array A. I also know how many numbers I want to shift.
I need, (e.g. shift left 2 bits)
B = [1,2,3,6,7,8,4,5,9,10];
Or (e.g. shift left 1 bit)
B = [1,2,3,4,6,7,8,5,9,10];
Or (e.g. shift right 2 bits)
B = [1,2,3,4,5,9,10,6,7,8];
Thanks
Nur

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Accepted Answer

Nurahmed
Nurahmed on 24 Jun 2019
I am new to Matlab, but after one day struggle, I finally found the solution to my problem. It was fun!
A=1:10;
startPos=4;
numMove=2;
shiftBit=3; % minus--moveLeft; positive--moveRight; zero--don'tMove
B = A;
B(startPos+shiftBit:startPos+shiftBit+numMove-1)=A(startPos:startPos+numMove-1);
if shiftBit<=0
oldNum = A(startPos+shiftBit:startPos-1);
B(startPos+shiftBit+numMove:startPos+numMove-1)=oldNum;
else
oldNum = A(startPos+numMove:startPos+numMove+shiftBit-1);
B(startPos:startPos+shiftBit-1)=oldNum;
end

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More Answers (1)

dpb
dpb on 23 Jun 2019
Sorta' inconsistent definition, but look at
>> A=1:10;
>> circshift(A(4:end-2),-2) % case 1
ans =
6 7 8 4 5
>>
>> circshift(A(6:end),2) % case 3
ans =
9 10 6 7 8
>>
Have to just decide what it means to "shift" -- the latter above is actually a circular shift of the elements within the total vector while the first is more like swapping positions of a lesser subset altho can be written with circshift but selecting proper subset of the overall vector and pre- or post-pending the remainders.
With only the examples but not the logic behind "why" the difference, it's your call as to how to decide what is what really want.

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