Create arrays from single array indexes

Lets say I have array A which contains the some unsigned numbers. The length of A is always even. I have following code which I want to convert into vectorizztion.

A= [10 20 30 50];
output = cell(1, length(A)/2);
j = 1;
for i=1:2:length(A)/2
  output(j) = A(i):A(i+1);
  j = j + 1;
end

All I want to avoid this loop.

[Stephen23]

So this is the code in your original question:

A= [10 20 30 50];
output = cell(1, length(A)/2);
j = 1;
for i=1:2:length(A)/2
  output(j) = A(i):A(i+1);
  j = j + 1;
end

When I run the code it throws this error:

??? Conversion to cell from double is not possible.
Error in ==> temp at 7
  output(j) = A(i):A(i+1);

And if I convert the code so that the variable output uses cell array indexing it generates the following output:

>> output
output = 
    [1x11 double]    []
>> output{1}
ans =
    10    11    12    13    14    15    16    17    18    19    20

Is this really what you intended?

Answer 1

[Azzi Abdelmalek]

out=arrayfun(@(x) A(x):A(x+1),1:numel(A)/2,'un',0)

But this is not faster then a for loop

Answer 2

[Stephen23]

Perhaps you intended it to do something like this:

>> A = [10 20 30 50];
>> B = arrayfun(@(b,e)b:e, A(1:2:end), A(2:2:end), 'UniformOutput',false)
B = 
    [1x11 double]    [1x21 double]
>> B{1}
ans =
    10    11    12    13    14    15    16    17    18    19    20
>> B{2}
ans =
  Columns 1 through 16
    30    31    32    33    34    35    36    37    38    39    40    41    42    43    44    45
  Columns 17 through 21
    46    47    48    49    50

Answer 3

[Walter Roberson]

http://blogs.mathworks.com/loren/2008/10/13/vectorizing-the-notion-of-colon/