How to code this? Resampling of vector

Hi all,

Currently I am trying to resample a signal by changing its signal frequency; The signal is given by time vector t and signal vector s. Example:

t=[ 1 2 3 4 5 6 7 8 9 10 11 12]

s=[3 3.5 3 5.5 2 2.5 3 5 7 2.5 3.5 4 ]

I want to create a vector s_new in which the sum of the values of s on the interval <0,4] is one element, the sum of interval <4,8] is an element etc, creating:

s_new= [15 12.5 17]

I have been toying around with histc but didnt succeed. Any ideas on coding this?

Thanks in advance! Lucas

[Azzi Abdelmalek]

Lucas commented

Thanks guys, but I actually want to use any resampling frequency, so the reshape command doesnt necessarily work (works only if old and new sampling times are integer multiples of each other). Thanks anyway!

Answer 1

[Mischa Kim]

For these straightforward time values, this will do

sum(reshape(s,4,3))

If t gets more complex you should be able to find a similar solution, though.

Answer 2

[David Sanchez]

s_new(1) = sum(s(find(s<4)))
s_new(2) = sum(s(find( (s<8)&(s>=4) )))
s_new(3) =sum(s(find( (s<12)&(s>=8) )))
...

Answer 3

[Azzi Abdelmalek]

t=[ 1 2.5 2.8  3 3.1  4 5 6 7 8 9 10 11 12];
s=[3 3.5 3.5 4 3 5.5 2 2.5 3 5 7 2.5 3.5 4 ]
ii=hist(t,[2 6 10]) % 2 is the middle of the interval [0,4];
ii2=cumsum(ii);
ii1=[1 ii2(1:end-1)+1]; 
out=arrayfun(@(ii,jj) sum(s(ii:jj)),ii1,ii2)

[Lucas]

Thank you! Works great.