# How to replace a number in a row vector with NaN in certain condition

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Yared Daniel on 29 May 2021
Commented: Yared Daniel on 30 May 2021
I have raw vector like this
x = [15 13 9 20 12 15 2 25 17 3 2 5 18 4 12 30 32 40 1 19];
What I need is to replace a number with NaN when the following condition happen.
Whenever the abs difference between x(i) and x(i+1) is >10 replace x(i+1) with NaN , and continue next computation between x(i) and x(i+2) by skipping the value that is assigned as ‘NaN’. If the abs diff between x(i) and x(i+2) is <10, Then the next computation has to be between x(i+2) and x(i+3). But if the abs diff between x(i) and x(i+2) was >10, x(i+2) would be replace by ‘Nan” and next computation would be between x(i) and x(i+3).
In similar way computation continue and returned result should be as follow
x_new = [15 13 9 NaN 12 15 NaN NaN 17 NaN NaN NaN 18 NaN 12 NaN NaN NaN NaN 19]

per isakson on 29 May 2021
Edited: per isakson on 29 May 2021
abs(x(6)-x(8)) is equal to 10. Accourding to x_new, x(8) should be replaced by NaN. Thus I have use ">=".
%%
vec = [15 13 9 20 12 15 2 25 17 3 2 5 18 4 12 30 32 40 1 19];
len = numel( vec );
new = vec;
pos = 1;
for jj = 2 : len
if abs(vec(pos)-vec(jj)) >= 10 % Notice ">="
new(jj) = nan;
else
pos = jj;
end
end
%%
x_new = [15 13 9 NaN 12 15 NaN NaN 17 NaN NaN NaN 18 NaN 12 NaN NaN NaN NaN 19];
disp( x_new ), disp( new )
15 13 9 NaN 12 15 NaN NaN 17 NaN NaN NaN 18 NaN 12 NaN NaN NaN NaN 19 15 13 9 NaN 12 15 NaN NaN 17 NaN NaN NaN 18 NaN 12 NaN NaN NaN NaN 19
Yared Daniel on 30 May 2021
Thank you so much for understanding my question and solving exactly what I need