MATLAB: Keep element greater than immediate previous element

vector loop

Hi,
x = [1 2 3 4 3 2 3 4 6 8 5 5 6 8.5 9 11 12 ]; I want to keep one vector whereby the next element is greater than the immediate previous element. keep = [[1 2 3 4 6 8 8.5 9 11 12 ]; to discard if the element is smaller than or equal to the immediate previous element. discard = [3 2 3 4 5 5 6] (the bold elements in x).
I am using loop to do that and I didn't get what I want. could help modify my code or advise any alternative way? thanks in advance!
clc; clear; close all
x = [1 2 3 4 3 2  3 4 6 8  5  5 6 8.5  9  11 12 ];
m = length(x);
k=1; n = 1; i =1; j=2;
while i < m-1  & j < m      
        if x(j) >= x(i)
         keep(n) = x(j);   
          n=n+1; 
          i=i+1;
          j=j+1;
        elseif x(j) < x(i)
            discard(k) = x(j);
            k = k+1;
            i=i;
            j=j+1;
        end
    
end

Best Answer

This loops does what you want:
x = [1 2 3 4 3 2  3 4 6 8  5  5 6 8.5  9  11 12 ];
m = length(x);
keep = [x(1)];
discard =[];
for idx=2:m
    if x(idx)>keep(end)
        keep = [keep,x(idx)];
    else
        discard = [discard,x(idx)];
    end
    
end
keep
discard
keep =
    1.0000    2.0000    3.0000    4.0000    6.0000    8.0000    8.5000    9.0000   11.0000   12.0000
discard =
     3     2     3     4     5     5     6
Although, depending of your goal, simply sorting the array could solve the problem in a more simplified way:
keep = unique(sort(x))
keep =
    1.0000    2.0000    3.0000    4.0000    5.0000    6.0000    8.0000    8.5000    9.0000   11.0000   12.0000
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