Swap the first and last columns

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Zunaed Kibria
Zunaed Kibria 2018-12-16
回答： ARVIND KUMAR SINGH 2020-5-25
function B = swap_ends(A)
B = A(:,[end , 2:end-1 , 1]);
end
tried this , but showing error , can any one help ?

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回答（4 个）

Alessandro Galo
Alessandro Galo 2019-3-26
This works ;)
if size(A,2) ~= 1 & size(A,2) ~= 0
B = A(:,[end , 2:end-1 , 1])
else
B = A;
end
madhan ravi
madhan ravi 2018-12-16
编辑：madhan ravi 2018-12-16
A=rand(4) % example matrix
B = swap_ends(A) % function call
function B = swap_ends(A) % function definition
A(:,[1 end])=A(:,[end 1]);
B=A;
end
Gives:
A =
0.5200 0.8475 0.4965 0.0832
0.7875 0.0289 0.0663 0.1867
0.2765 0.5650 0.1179 0.9095
0.0962 0.7098 0.3063 0.6303
B =
0.0832 0.8475 0.4965 0.5200
0.1867 0.0289 0.0663 0.7875
0.9095 0.5650 0.1179 0.2765
0.6303 0.7098 0.3063 0.0962
A=rand(1,5) % example row vector/column vector
B = swap_ends(A) % function call
function B = swap_ends(A) % function definition
A([1 end])=A([end 1]);
B=A;
end
Gives:
A =
0.6604 0.9767 0.4717 0.8576 0.9269
B =
0.9269 0.9767 0.4717 0.8576 0.6604
  1 个评论
Walter Roberson
Walter Roberson 2019-3-26
编辑：Walter Roberson 2019-3-26
Alessandro Galo's solution does raise the good point that swapping using end subscript will fail if the array is empty on that dimension, so the swap should be protected with isempty()

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Sunil Kumar Giri
Sunil Kumar Giri 2020-1-13
function B = swap_ends(A)
B = A;
A(:,1) = A(:,end);
A(:,end) = B(:,1);
B = A
end
ARVIND KUMAR SINGH
ARVIND KUMAR SINGH 2020-5-25
function B = swap_ends(A)
[~,col] = size(A);
if col<2
B = A;
else
a = A(:,1);
b = A(:,col);
c = A(:,2:col-1);
B =[b c a];
end
end

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