Sum in groups of ones and zeros

Question

Gina Torres 2018-7-18

回答： Paolo 2018-7-18

Hello all,

I have two vectors. In the form:

 idx=[1;1;1;1;0;0;0;1;0;1;1;0;0] 
 p=[0.2;0.3;1;0.89;0.35;0.25;0.74;0.98;0.25;0.24;0.15;0.75;0.125].

I want to sum the numbers corresponding to the different groups of ones and zeros. The result would be:

 ans1=[2.39;0.98;0.39]
 ans2=[1.34;0.25;0.875]

Thank you

Answer 1

Paolo 2018-7-18

A possible solution:

For ones:

 [sindx,endindx] = regexp(char(idx+'0')','1*')
 indx = arrayfun(@(x,y) x:y,sindx,endindx,'un',0)
 ans1 = cellfun(@(x) sum(p(x)),indx)

For zeros:

 [sindx,endindx] = regexp(char(idx+'0')','0*')
 indx = arrayfun(@(x,y) x:y,sindx,endindx,'un',0)
 ans2 = cellfun(@(x) sum(p(x)),indx)