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

Question

Yared Daniel 2021-5-29

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/843095-how-to-replace-a-number-in-a-row-vector-with-nan-in-certain-condition

评论： Yared Daniel 2021-5-30

采纳的回答： per isakson

在 MATLAB Online 中打开

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]

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Answer 1

per isakson 2021-5-29

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/843095-how-to-replace-a-number-in-a-row-vector-with-nan-in-certain-condition#answer_712335

编辑：per isakson 2021-5-29

在 MATLAB Online 中打开

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