extract numbers from time series

Have a time series from 1 to 156. Want to extract the values from 1:6, then from (1+12) : (6+12), etc into a new variable. How to go about.

[Adam Danz]

That's not enough in your example for anyone to extrapolate the pattern you seek. For example, would the subunits be 1:6, 13:18, 14:19, 15:20? Or 1:6, 13:18, 19:24,... ?

[Johannes Deelstra]

ok I will try to be more specific. Actually it is a matrix with monthly values. Columns 1:4 contain calcualted mean values of parameters I am interested in, while column 5 contains the months/dates from may 1992 until april 2005. Now I want from this time series for each year the values for the parameters I am interested in, which are those for the months of May until October. So how can I do this, obtain the values for the parameters in columns 1 to 4 plus the datevalues in column 5 Thanks in advance

[Adam Danz]

What format are your dates in?

class(data(:,5))

[Johannes Deelstra]

the dates are numbers such as 33725 33756 33786 33817 33848 33878 33909 33939 33970 34001 34029

[Adam Danz]

Ok. If the numbers are serial date numbers that matlab recognizes, my solution should work well. Otherwise, we'd just need to convert them to a format that Matlab recognizes which should be fairly simple.

[Johannes Deelstra]

i solved the problem, thanks for your help and suggestions

Answer 1

[Adam Danz]

I don't know what format your dates are in but this can be adapted to any format. I assume your matrix is named 'data' and the dates are in the 5th column.

% Get the month number for each date
monthNum = month(data(:,5)); 

% Logical index of rows that are between May and October
monthIdx = ismember(monthNum, [5:10]); 

% Extract your data for these months
data(monthIdx, :)

Answer 2

[Fangjun Jiang]

a=1:156;
b=reshape(a,6,[]);
c=b(:,1:2:end)

[Johannes Deelstra]

see my answer to the question I got from Adam. Tried to be more specific.

[Johannes Deelstra]

the dates are numbers, such as 33725 33756 33786 33817 33848 33878 33909 33939 33970 34001 34029