Append to vector of different sizes in for loop

Hi.

How does one append a vector to a another vector within a loop.

I have the code below: Point is i want the signal between the first and second indices of ipts. then the third and fourth et cetera up to the nineteenth to twentieth.

with this code I only get the last part nineteenth to twentieth.

i = 1;
while i < 19;
    A = TimeSeries_short(ipts(i):ipts(i+1));
    i = i+2;
end

.mat file is attached.

Answer 1

[Stephen23]

Simpler:

S = load('test_file.mat')

S = struct with fields:
    TimeSeries_short: [1×47000 single]
                ipts: [1182 3977 5678 8607 10129 13100 14657 17610 19172 22121 23650 26578 28197 31090 32741 35696 37300 40136 41691 44808]

fun = @(b,e)S.TimeSeries_short(b:e);
out = arrayfun(fun,S.ipts(1:2:end),S.ipts(2:2:end),'uni',0)

out = 1x10 cell array
    {1×2796 single}    {1×2930 single}    {1×2972 single}    {1×2954 single}    {1×2950 single}    {1×2929 single}    {1×2894 single}    {1×2956 single}    {1×2837 single}    {1×3118 single}

https://www.mathworks.com/help/matlab/matlab_prog/access-data-in-a-cell-array.html

[Jørgen Fone Pedersen]

Thank you.

This works great

Answer 2

[dpb]

The short answer is

i = 1;
A=[];
for i=1:2:numel(ipts)
  A = [A;TimeSeries_short(ipts(i):ipts(i+1),:);
end

Normally one frowns on dynamic reallocation, but presuming the overall array is going to be relatively small, the time taken won't be excessive.

If A is going to be very large, then one will want to calculate the final size and compute the indices going in and explicitly set the rows.

[Jørgen Fone Pedersen]

Thank you.

[Jørgen Fone Pedersen]

Sorry but this didnt work actually.

I get this message, its probably a simple typo but im not able to correct it.

Index in position 1 exceeds array bounds (must not exceed 1).

Error in Test_file (line 43)

A = [A;TimeSeries_short(ipts(i):ipts(i+1),:)];

any ideas?

[dpb]

Need rest of the error message in context to be able to identify which array it didn't like..

What does

whos ipts TimeSeries_short

return?

[Jørgen Fone Pedersen]

>> whos ipts TimeSeries_short
  Name                  Size                Bytes  Class     Attributes

  TimeSeries_short      1x51212            204848  single              
  ipts                  1x20                  160  double              

>> 

It doesnt give any other error message than the one i posted previously :/

[dpb]

OK, I presumed a column-wise array, not a vector.

Hence I referenced

T(i1:i2,:)

to pull all rows of the array T, not just a single column. For a vector need just the 1D indexing expression.

 A = [A;TimeSeries_short(ipts(i):ipts(i+1))];

instead for a vector (column output); replace semi-colon with comma for row output.

[Jørgen Fone Pedersen]

ahh, thank you.