How to iterate through an array to check for adjacent elements that are equal to one another using loops.

%This loads the file and allows us the work with the 'nr' varible
load("m05.mat")

%Varible for vector one. This vector will display all the indices of the
%elements meeting the condition
%V1 = nr;

%position one and position two in the array 'nr'
p1 = sym(nr(:,1));
p2 = sym(nr(:,2));


%Varible for vector two. This vector will display all of the values of the
%elements that meet the condition
%V2 = nr;

%% Section 2: Processing


%Loop to find the values for V2
for i = 1:1:1000
    if p1 == p2
        disp(p1)
        disp(p2)
        
    end
    p1 = sym(nr(:, +1)); %I want p1 and p2 to be reassinged to the next
%element in the array 'nr'. 'nr' contains 1000 elements. I want the loop to
%check if adjacent elements in my loop are equal. For example if nr was
%equal to [1, 2, 2, 3], I would want it to display: '2' '2', at indices 2
%and 3. 
    p2 = sym(nr(:, +1));
end

[KALYAN ACHARJYA]

Can you share sample example rather that the mat file?

Answer 1

[KALYAN ACHARJYA]

"How to iterate through an array to check for adjacent elements that are equal to one another using loops"

Here a is an 1D array here

idx=zeros(1,length(a));
for i=1:length(a)
    switch i
        case 1
        if a(i)==a(i+1) 
        idx(i)=1;
        end
        case length(a)
        if a(i)==a(i-1) 
        idx(i)=1;
        end
        otherwise
        if a(i)==a(i-1) || a(i)==a(i+1)
        idx(i)=1;
        end 
    end 
end 
idx

[KALYAN ACHARJYA]

idx result shows 1, if adjacent are equal, otherwise 0

[Serena Simpson]

Thank you! I used a case switch in my program and it did work. I was trying to force it with while and if then loops. A switch makes more sense.

[Ron Fredericks]

Fun fact: if numbers to compare were floats instead of integers. The if statements could use ismembertol function instead of equals comparison. I reused this nice bit of code shared by @KALYAN ACHARJYA for graphics zoom error test. Sample code change :

if ismembertol(a(1), a(2))
    % ...
end