Dynamic window forming in efficient way in MATLAB - matlab

Question

Can someone help me to provide an efficient way or help me to perform the provide code to do make same results in minimal possible steps. I shall be grateful to you.
I have an Original Array:
A = [1 1 1 4.3 4.5 4 4.3 3 1 0 0 2 6.2 6.3 6 6.2 7.4 8 7.2 2 2 3 3 2];
Output Looks like:
A = [1 1 1 4 4 4 4 3 1 0 0 2 6 6 6 6 6 7 7 2 2 3 3 2];
I apply some restrictions and removed some values from array of local maxima’s after that I received some new arrays.
Yposlocfiltered = [6 15 23];
idx = [4 6 3];
Yneglocfiltered = [2 9 20];
idx_neg = [1 1 2];
Where I will find idx(local maxima value) I will check if values behind and ahead are greater make a window.
Example
If I will find 4 and 4.5, 4.3 is greater than 4 include it in backward window
4.3 is greater than 4 include it in forward window.
I need to find range of values behind local maxima and ahead local maxima.
I have tried to write a code that’s works fine but issue is that it’s too long.
Can someone please provide me an idea to perform this action in minimal steps and in faster ways?
I have only provided code for positive local maxima’s as for negative local maxima code Is just replica of this.
Code:only for positive local maximas
clc
clear all
A = [1 0 1 4.3 4.5 5 4.3 3 0 0 0 2 6.2 6.3 7 6.2 7.4 8 7.2 1 2 3 4 2];
Yposlocfiltered = [ 6 15 23];
idx = [4 6 3];
Yneglocfiltered = [2 9 20];
idx_neg = [1 1 2];
for b = 1: numel(idx)
for c = 1:numel(A)
f = Yposlocfiltered(1,b)-c ;
g = Yposlocfiltered(1,b)+c ;
% if (f > 0 && g <= numel(X))
if(f > 0)
if (A(Yposlocfiltered(1,b)-c))> idx(1,b)
else
d= f+1;
z(b)= d;
backward_window = z;
break
end
end
end
end
for r = 1: numel(idx)
for s = 1:numel(A)
u = Yposlocfiltered(1,r)-s ;
v = Yposlocfiltered(1,r)+s ;
% if (f > 0 && g <= numel(X))
if(v <=numel(A))
if (A(Yposlocfiltered(1,r)+s))> idx(1,r)
else
w= v-1;
y(r)= w;
forward_window = y;
break
end
end
end
end
n=4
for i=1:length(backward_window)
range = backward_window(i): forward_window(i);
p = range
if n <= numel(p)
p = range(1:n)
A( p) = idx(i);
else
% if (size(range)<= 3)
A( p) = idx(i);
end
end

Answer 1

From the first look at your code, I believe you can combine your first two for loops into one.
sA = numel(A);
sI = numel(idx);
for i = 1:sI
f = Yposlocfiltered(i) - [1:sA];
g = Yposlocfiltered(i) + [1:sA];
f(f<1) = [];
g(g>sA) = [];
backward_window(i) = f(find(A(f) <= idx(i), 1)) + 1;
forward_window(i) = g(find(A(g) <= idx(i), 1)) - 1;
end
Here, you can use find to locate the element of an array matching the specified condition, i.e. g <= numel(X) or A(f) <= idx(i).
Your last loop which modifies A can also be integrated into the same loop, so you can have:
sA = numel(A);
sI = numel(idx);
n=4;
for i = 1:sI
f = Yposlocfiltered(i) - [1:sA];
g = Yposlocfiltered(i) + [1:sA];
f(f<1) = [];
g(g>sA) = [];
backward_window(i) = f(find(A(f) <= idx(i), 1)) + 1;
forward_window(i) = g(find(A(g) <= idx(i), 1)) - 1;
range = backward_window(i) : forward_window(i);
if n <= numel(range)
A(range(1:n)) = idx(i);
else
A(range) = idx(i);
end
end