Generating sequences from data

Hi All,

I have a data set (x1, x2, x3, x4, x5, x6, x7, .... xn) from which I want to generate sequences like

x1, x2, x3, x4, x5

x2, x3, x4, x5, x6

x3, x4, x5, x6, x7

x4, x5, x6, x7, x8

..................... xn

Thank you

Answer 1

[Andrei Bobrov]

xy = [5    14
     6    16
     1    16
     6    11
     4    16
     1    16
     2    13];

n = 5;
[m,k] = size(xy);
out = xy(reshape(hankel(1:n,n:m),1,n,[]) + m*(0:k-1)')

[Mahendran Subramanian]

Thank you for the answer, however, Iam getting the following error

"You cannot subscript a table using linear indexing (one subscript) or

multidimensional indexing (three or more subscripts). Use a row subscript and a

variable subscript."

[Andrei Bobrov]

Attach your table here as part of the mat file.

[Mahendran Subramanian]

RelativeX = 2500 x 1 double

RelativeY = 2500 x 1 double

or

XY = 2500 x 2 double

[Andrei Bobrov]

XY = readtable('XY.xlsx');
xy = XY{:,:};
n = 5;
[m,k] = size(xy);
out = xy(reshape(hankel(1:n,n:m),1,n,[]) + m*(0:k-1)');

[Mahendran Subramanian]

works thank you

Answer 2

[John D'Errico]

So, given a vector x, of length n, you want to create the array with rows that are the sub-sequences of length 5? The result will be a (n-4) x 5 array.

A trivial solution would just concatenate columns to create the array. However, that would not be easily fixed if you then wnted to create sub-sequences of length 6 or 4.

So far better is to create an index array, then use that to index into the vector.

n = length(x);
m = 5;
ind = (1:n-m+1)' + (0:m-1);
A = x(ind);

This works for any length vector, and any size of sub-sequences.

It does use a feature of MATLAB that was introduced in R2016b, to create the index array ind. Earlier releases might use this instead:

ind = bsxfun(@plus,(1:n-m+1)',0:m-1);

[Mahendran Subramanian]

Thank you for the answer, much helpful, and what if the data is arranged like (n x 2) array

x1 y1

x2 y2

x3 y3

x4 y4

x5 y5

. .

xn yn

and I want to get n number of (2 x 5) arrays

1st sequence (2 x 5) array

x1, x2, x3, x4, x5

y1, y2, y3, y4, y5

2nd sequence (2 x 5) array

x2, x3, x4, x5, x6

y2, y3, y4, y5, y6

3rd sequence (2 x 5) array

x3, x4, x5, x6, x7

y3, y4, y5, y6, y7

4rth sequence (2 x 5) array

x4, x5, x6, x7, x8

y4, y5, y6, y7, y8

..................... xn

[John D'Errico]

First, DON'T make different arrays for each sequence. That is a programming style that will serve you terribly badly in the future. Instead, learn to use multidimensional arrays. Or cell arrays, etc.

As far as your problem goes, you just have TWO vectors, x and y. You already know how to solve the problem for a vector. (I just showed you in my answer.) So get theanswer for each vector of x and y, and then figure out how to combine them into ONE large array, in this case, it would be a 3-dimensional array.

[Mahendran Subramanian]

I have already done that. I need the data as separate sequences for running through various analyses. And I am looking into it.

[Stephen23]

"I need the data as separate sequences for running through various analyses."

Then you can easily use an ND array or a cell array, exactly as John D'Errico wrote.

Answer 3

[Dwarka Sahu]

for i=1:5

sprintf('%g, %g, %g, %g, %g',i, i+1, i+2, i+3, i+4)

end

[Mahendran Subramanian]

Thank you for the answer, much helpful, and what if the data is arranged like (n x 2) array

x1 y1

x2 y2

x3 y3

x4 y4

x5 y5

. .

xn yn

and I want to get n number of (2 x 5) arrays

1st sequence (2 x 5) array

x1, x2, x3, x4, x5

y1, y2, y3, y4, y5

2nd sequence (2 x 5) array

x2, x3, x4, x5, x6

y2, y3, y4, y5, y6

3rd sequence (2 x 5) array

x3, x4, x5, x6, x7

y3, y4, y5, y6, y7

4rth sequence (2 x 5) array

x4, x5, x6, x7, x8

y4, y5, y6, y7, y8

..................... xn

[Dwarka Sahu]

For the first sequence of (nx2)

for i=1:5
sprintf('x%g, y%g', i, i)
end

For the next set of sequence of (2x5)

for i=1:5
sprintf('x%g, x%g, x%g, x%g, x%g', i, i+1,i+2,i+3,i+4)
sprintf('y%g, y%g, y%g, y%g, y%g', i, i+1,i+2,i+3,i+4)
end

[Mahendran Subramanian]

RelativeX = 2500 x 1 double

RelativeY = 2500 x 1 double

or

XY = 2500 x 2 double

Thank you for the answer, however, Iam getting the following

>> for i=1:5

sprintf('RelativeX%g, RelativeY%g', i, i)

end

for i=1:5

sprintf('RelativeX%g, RelativeX%g, RelativeX%g, RelativeX%g, RelativeX%g', i, i+1,i+2,i+3,i+4)

sprintf('RelativeY%g, RelativeY%g, RelativeY%g, RelativeY%g, RelativeY%g', i, i+1,i+2,i+3,i+4)

end

ans =

'RelativeX1, RelativeY1'

ans =

'RelativeX2, RelativeY2'

ans =

'RelativeX3, RelativeY3'

ans =

'RelativeX4, RelativeY4'

ans =

'RelativeX5, RelativeY5'

ans =

'RelativeX1, RelativeX2, RelativeX3, RelativeX4, RelativeX5'

ans =

'RelativeY1, RelativeY2, RelativeY3, RelativeY4, RelativeY5'

ans =

'RelativeX2, RelativeX3, RelativeX4, RelativeX5, RelativeX6'

ans =

'RelativeY2, RelativeY3, RelativeY4, RelativeY5, RelativeY6'

ans =

'RelativeX3, RelativeX4, RelativeX5, RelativeX6, RelativeX7'

ans =

'RelativeY3, RelativeY4, RelativeY5, RelativeY6, RelativeY7'

ans =

'RelativeX4, RelativeX5, RelativeX6, RelativeX7, RelativeX8'

ans =

'RelativeY4, RelativeY5, RelativeY6, RelativeY7, RelativeY8'

ans =

'RelativeX5, RelativeX6, RelativeX7, RelativeX8, RelativeX9'

ans =

'RelativeY5, RelativeY6, RelativeY7, RelativeY8, RelativeY9'