我如何給行替換上述

Question

連續NaN的元素具有以下矩陣

A = [ 0 0 
     0 0 
     1 -1 
    NaN NaN 
    NaN NaN 
     0 0 
    NaN NaN 
    NaN NaN] 

我要全部更換爲NaN行與它上面行。對於上面的矩陣，這將是

A = [0 0 
    0 0 
    1 -1 
    1 -1 
    1 -1 
    0 0 
    0 0 
    0 0] 

Answer 1

我不知道這是否可以矢量...的簡單的解決方案可能是一個循環：

newRow = []; 
nans = isnan(A(:,1)); 
for ii = 1:size(A,1) 

    if nans(ii) 

     %# first row might be NaN -- skip it 
     if ii==1 
      continue; end 

     %# for all other rows: 
     if isempty(newRow) 
      newRow = A(ii-1,:); end 

     A(ii,:) = newRow; 

    else 
     newRow = []; 
    end 

end 

Answer 2

一個想法是先創建一個壓縮矩陣B，其不與NaN包含的行，然後再次擴大該矩陣是相同的長度的與原始矩陣：

mask = any(isnan(A), 2); 
B = A(~mask, :); 
result = B(cumsum(~mask), :);