How to replace duplicate elements with the elements of the second array?
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Hi , I have two arrays , one with duplicate elements and I want to keep the first occurance of the element and replace other repeated values with the elements of the second array. Here is the example
a=[23 34 56 78 100 10 12];
b= [2 2 2 4 6 0 0 11 11 11 6];% contains repeating elements
iwant=[2 23 34 4 6 0 56 78 11 100 10 12]
6 Comments
Dyuman Joshi
on 1 Feb 2023
Let's go through the elements -
a=[23 34 56 78 100 10 12];
b= [2 2 2 4 6 0 0 11 11 11 6];
Starting with 2nd index
index 2, b(2) appears before, replaced by a(1), [2 23 2 4 6 0 0 11 11 11 6]
index 3, b(3) appears before, replaced by a(2), [2 23 34 4 6 0 0 11 11 11 6]
index 4, b(4) doesn't appear before
index 5, b(5) doesn't appear before
index 6, b(6) doesn't appear before
index 7, b(7) appears before, replaced by a(3), [2 23 24 4 6 0 56 11 11 11 6]
index 8, b(8) doesn't appear before
index 9, b(9) appears before, replaced by a(4), [2 23 24 4 6 0 56 11 78 11 6]
index 10, b(10) appears before, replaced by a(5), [2 23 24 4 6 0 56 11 78 100 6]
index 11, b(11) appears before, replaced by a(6), [2 23 24 4 6 0 56 11 78 100 10]
Now, appending remaining elements of a (7 to end) to b, [2 23 24 4 6 0 56 11 78 100 10 12]
which is different from iwant=[2 23 34 4 6 0 56 78 11 100 10 12]
It seems that there's a mistake in iwant. I insist you clarify this.
Accepted Answer
Voss
on 31 Jan 2023
Maybe something like this?
a = [23 34 56 78 100 10 12];
b = [2 2 2 4 6 0 0 11 11 11 6];% contains repeating elements
yougot = b;
a_idx = 1;
for ii = 1:numel(b)
if any(b(1:ii-1) == b(ii))
yougot(ii) = a(a_idx);
a_idx = a_idx+1;
end
end
if a_idx <= numel(a)
yougot = [yougot a(a_idx:end)];
end
disp(yougot);
iwant = [2 23 34 4 6 0 56 78 11 100 10 12];
disp(iwant);
Note that the 11 and the 78 are switched in iwant vs yougot. I think that's a mistake in iwant, according to the description of the algorithm you gave.
More Answers (1)
Fabio Curto
on 31 Jan 2023
Hi,
If i get the question correctly, you want to append the remaining unused elements of a. I wrote a basic idea, maybe it can be optimized in some way!
a=[23 34 56 78 100 10 12];
b= [2 2 2 4 6 0 0 11 11 11 6];% contains repeating elements
changed = 1; % flag initialization
j = 1; % a vector index
for i=2:length(b)
if changed == 1
temp = b(i-1);
end
if b(i) == temp
b(i) = a(j);
j = j+1;
changed = 0;
else
changed = 1;
end
end
for j=j:length(a)
b = [b a(j)];
end
Hope it is helpful,
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