campare a row value with the next row

Hi

I have the following column:

1

1

0

0

0

1

0

1

0

1

I want to campare rows value one by one with the next row ( first with second, second with third ... and ninth with tenth) and check if it changes for 1 to 0, 0 to 0, 0 to 1 and 1 to 1. For each of these conditions, I want to count them. I tried using loop and diff or sign and equations but I could not work out because the results will be similar for two conditions.

Answer 1

[Rik]

You were close when using diff. You need to think what characterizes all four combinations. The code below should be what you need.

v=[1;1;0;0;0;1;0;1;0;1];

d=diff(v);
u=v(1:(end-1));%shrink by 1 to make it the same size as d

clc
%if [0;0]
%then diff==0, v==0
L= d==0 & u==0;
fprintf('[0 0]: %d\n',sum(L))

%if [0;1]
%then diff==-1
L= d==-1;
fprintf('[0 1]: %d\n',sum(L))

%if [1;0]
%then diff==1
L= d==1;
fprintf('[1 0]: %d\n',sum(L))

%if [1;1]
%then diff==0, v==1
L= d==0 & u==1;
fprintf('[1 1]: %d\n',sum(L))

[Boby S]

Thanks

Answer 2

[Alex Mcaulley]

Another option:

a = [1;1;0;0;0;1;0;1;0;1];

b = diff(a);
b(~b) = 2*a(~b);
sol = splitapply(@numel,b,b+2) %Ordered as [1,0],[0,0],[0,1],[1,1]

sol =

     3     2     3     1

[Boby S]

Thanks

[Boby S]

Dear Alex

I have two problem when I want to use this code in a loop. diff gives 0 result for both changes from 1 to 1 and 0 to 0. When I use it without loop I got 2 (for 1 to 1) and 0 for 0 to 0 (like the code above). The other thing is when the count for one condition is 0 and I do not see 0 in results and I see only three result which is confusing. The code below is what I tried.

my data: 2*20 >>> I want to calulate the second column.

0	0
0	1
1	0
0	0
1	0
0	1
1	0
1	1
0	0
1	1
1	1
0	0
0	1
1	0
0	1
0	1
0	1
1	1
1	0
1	1

converted = table2array(imported);
n=2;
C=permute(reshape(converted,10,n,2), [1 3 2]); 
for ind = 1:n
  D = C(:,2,ind);  
  b = diff(D);
  b(~b) = 2*D(~b);
  sol= splitapply(@numel,b,b+2);
  soll{ind}=sol
end


Error using splitapply (line 111)
For N groups, every integer between 1 and N must occur at least once in the vector of group numbers.

[Alex Mcaulley]

With your second column it should work fine, because you have all the possible combinations.

[Boby S]

I think this is the reason:

https://de.mathworks.com/matlabcentral/answers/466227-error-in-appliying-split-apply#answer_396051

I think if one condition result is 0 then I will get the error.