Repalce zero element by the number before it ?

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Willim
Willim 2019-1-17
编辑： madhan ravi 2019-1-17
If I have array called N,
N = [2 0 7 0 9 10 0 0 11 0 0 ];
I want to create new array M that have [2 2 7 7 9 10 10 10 11 11 11]
Here is other example
N=[ 0 1 4 5 6 7 0 10 0 0 0]
the one I would create is
M=[0 1 4 5 6 7 7 10 10 10 10].
I would replace each zero in array N by the number before it except the first zero.
Thank you in advance.

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采纳的回答

Image Analyst
Image Analyst 2019-1-17
Faraj:
Did you try the super obvious solution: a very simple "for" loop:
N = [2 0 7 0 9 10 0 0 11 0 0 ];
for k = 1 : length(N)
if N(k) == 0
N(k) = N(k-1);
end
end
Presumably so. Were you looking for some more compact vectorized or function-based solution instead?

更多回答（2 个）

KSSV
KSSV 2019-1-17
N=[ 0 1 4 5 6 7 0 10 0 0 0] ;
M = N ;
idx = find(N==0) ; % get the indices of zeros
while ~isempty(idx)
idx(idx==1) = [] ; % remove the index if zero is at one
M(idx) = M(idx-1) ; % replace zeros with previous values
idx = find(M==0) ;
idx(idx==1) = [] ;
end
  2 个评论
Willim
Willim 2019-1-17
This works but for my entire code , my code keeps running until I pause the run and quit debugging. then type M in my command window then I got the right M.
could you please the algorithm code ?
KSSV
KSSV 2019-1-17
Give the value of N. Image Analyist solution is good....go ahead with that.

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madhan ravi
madhan ravi 2019-1-17
编辑：madhan ravi 2019-1-17
EDITED
N = [2 0 7 0 9 10 0 0 11 0 0 ];
M=N;
M(M==0)=NaN;
M=fillmissing(M,'nearest')
Gives:
M =
2 2 7 7 9 10 10 10 11 11 11
N=[ 0 1 4 5 6 7 0 10 0 0 0];
M=N;
M(M==0)=NaN;
M=fillmissing(M,'previous');
M(1)=0
Gives:
M =
0 1 4 5 6 7 7 10 10 10 10
  5 个评论
显示 3更早的评论
Willim
Willim 2019-1-17
great it works but the thing is that the frist element could be 1 not 0 all the time
madhan ravi
madhan ravi 2019-1-17
编辑：madhan ravi 2019-1-17
What? Did you see the first example in my answer?

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