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half the first NaN value after the last non NaN value in each column

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Qian cao
Qian cao 2015-11-30
关闭： MATLAB Answer Bot 2021-8-20
Hi, I have a matrix
p = [NaN 2 NaN;
2 4 NaN;
2 6 8;
NaN 8 2;
NaN NaN 1;
NaN NaN 1]
The realized matrix
p1 = [NaN 2 NaN;
2 4 NaN;
2 6 8;
1(half of 2) 8 2;
NaN 4(half of 8) 1;
NaN NaN 1]
... Notice: Only the first NaN after the last non NaN value in each column is halved with the last non NaN value.. while the other NaN stay as they were.. Thank you for your answers. BR

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回答（2 个）

Jan
Jan 2015-11-30
编辑：Jan 2015-11-30
p = [NaN 2 NaN;
2 4 NaN;
2 6 8;
NaN 8 2;
NaN NaN 1;
NaN NaN 1];
m = isnan(p);
for col = 1:size(p, 2)
index = strfind(m(:, k).', [false, true]); % [EDITED]
if ~isempty(index)
p(index(1) + 1, k) = p(index(1), k) / 2;
end
end
  2 个评论
Jan
Jan 2015-11-30
Please, Qian cao, giv us any chance to post an improvement. Tell us, what goes wrong. Do you get an error message or does the result differ from your expectations? I see a little typo, which is fixed now. So try it again.
Thorsten
Thorsten 2015-11-30
ind = diff(isnan([p; p(end,:)])) == 1;
p(ind) = p(ind)/2;
  2 个评论
Qian cao
Qian cao 2015-11-30
No...it should be the cell after p(ind)...I tried with p(ind+1) = p(ind)/2; But it does not work...Could you help me ? In your result, the last non NaN is replaced...but I need to keep it and just fill the cell after it in the column with a value that is half of it...

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