How can I replace NaN elements with the nearest value in the same column?

2017 4 25
2 个回答
回答已采纳
更新时间：2017 4 27
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0 个投票

I am trying to replace NaN's in a vector field with the nearest value.
% I have:
M=
NaN 12
18 14
NaN NaN
NaN NaN
NaN 16
12 NaN
12 NaN
NaN 12
16 NaN
%I desire:
M=
18 12
18 14
12 16
12 16
12 16
12 12
12 12
16 12
16 12
Any information will be helpful. Thank you

2 个评论
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AstroGuy1984
AstroGuy1984 2017-4-25
编辑：AstroGuy1984 2017-4-25
What do you mean by "nearest"? Do you mean "next good value"? Because that's what you appear to desire. For example the second NaN in column 1 is closer to 18 than 12.
sal135
sal135 2017-4-26
I would like to have the first value of NaN to have the value of the next good value. However if the last value in the column is a NaN I would like for it to have the value of the previous good value

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 采纳的回答

Andrei Bobrov
Andrei Bobrov 2017-4-25
编辑：Andrei Bobrov 2017-4-26

1 个投票

FIXED 2
m = flipud(M)
t = ~isnan(m);
ii = cumsum(t);
ii(ii == 0) = 1;
ii = bsxfun(@plus,[0,ii(end,1:end-1)],ii);
m1 = m(t);
out = flipud(m1(ii))

6 个评论
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sal135
sal135 2017-4-26
I keep getting an error of: Undefined function 'flip' for input arguments of type 'double'.
Andrei Bobrov
Andrei Bobrov 2017-4-26
You are using an older version of MATLAB. Fixed for you.
sal135
sal135 2017-4-26
Yeah I just realized that. However now I get Error using + Matrix dimensions must agree.
Andrei Bobrov
Andrei Bobrov 2017-4-26
>> m = flipud(M);
t = ~isnan(m);
ii = cumsum(t);
ii(ii == 0) = 1;
ii = bsxfun(@plus,[0,ii(end,1:end-1)],ii);
m1 = m(t);
out = flipud(m1(ii))
out =
18 12
18 14
12 16
12 16
12 16
12 12
12 12
16 12
16 12
>>
sal135
sal135 2017-4-26
编辑：sal135 2017-4-27
Thank you for your help! This worked out great.

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