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how to separate string matrix by zeros

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Josh
Josh 2021-6-2
评论： Josh 2021-6-2
I imported some tables into matlab as string matrices. Each row contains 16 values. I would like to separte them by a group of zeros but don't know how to do it. For example, as highlighted on the imageI'd like to extract those three sections from the matrix, but don't know how to code the loop
k=1;
for i=1:size(m,1)
x = m(i,:);
str = sprintf('%s,', x{:});
num = sscanf(str, '%g,', [16, inf]);
val(:,k)=num;
if sum(val(:,k))~=0
% read more rows in until sum(num)==0
k=k+1;
else
end
end
  1 个评论
Rik
Rik 2021-6-2
What is your intended output? A cell vector with one section in each cell element?

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采纳的回答

Stephen23
Stephen23 2021-6-2
编辑：Stephen23 2021-6-2
Ran in:
This would have been easier if you had imported the data as numeric, rather than as string.
Rather than relying on low-level loops and inefficient array expansion the MATLAB approach would be to use indexing and handle the entire matrix or "non-zero blocks" at once. For example:
S = load('matlab.mat')
S = struct with fields:
m: [7195×1 string]
M = sscanf(sprintf('%s,',S.m),'%f,',[16,Inf]).' % convert to numeric
M = 7195×16
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 7 5 1 7 5 0 0 8 4 3 5 2 6 1 1 0 7 5 1 7 5 0 0 8 4 3 5 2 6 1 7 2 6 0 7 7 1 1 8 0 3 0 5 4 7 7 7 2 6 0 7 7 2 1 8 0 3 0 5 4 7 7 7 7 10 13 13 13 14 14 16 9 10 10 12 13 12 13 7 7 10 13 13 13 14 14 16 9 10 10 13 12 13 13 15 9 9 9 10 10 10 9 15 14 15 15 15 14 14 13
Your question is unclear what you expect for the output. If you want one numeric matrix with all "non-zero" rows in it, then just use basic MATLAB indexing:
X = any(M~=0,2);
Z = M(X,:)
Z = 6199×16
1 0 7 5 1 7 5 0 0 8 4 3 5 2 6 1 1 0 7 5 1 7 5 0 0 8 4 3 5 2 6 1 7 2 6 0 7 7 1 1 8 0 3 0 5 4 7 7 7 2 6 0 7 7 2 1 8 0 3 0 5 4 7 7 7 7 10 13 13 13 14 14 16 9 10 10 12 13 12 13 7 7 10 13 13 13 14 14 16 9 10 10 13 12 13 13 15 9 9 9 10 10 10 9 15 14 15 15 15 14 14 13 15 9 9 9 10 10 10 9 15 14 15 15 15 14 14 13 13 12 13 14 14 14 13 13 13 13 12 11 13 13 12 13 13 12 13 14 14 14 13 13 13 13 12 11 13 13 12 13
If you want to keep those "non-zero groups" separate then you should split them into a cell array:
D = diff([false;X;false]);
Y = find(D<0)-find(D>0);
C = mat2cell(M(X,:),Y,16);
Checking the first three matrices:
C{1:3}
ans = 12×16
1 0 7 5 1 7 5 0 0 8 4 3 5 2 6 1 1 0 7 5 1 7 5 0 0 8 4 3 5 2 6 1 7 2 6 0 7 7 1 1 8 0 3 0 5 4 7 7 7 2 6 0 7 7 2 1 8 0 3 0 5 4 7 7 7 7 10 13 13 13 14 14 16 9 10 10 12 13 12 13 7 7 10 13 13 13 14 14 16 9 10 10 13 12 13 13 15 9 9 9 10 10 10 9 15 14 15 15 15 14 14 13 15 9 9 9 10 10 10 9 15 14 15 15 15 14 14 13 13 12 13 14 14 14 13 13 13 13 12 11 13 13 12 13 13 12 13 14 14 14 13 13 13 13 12 11 13 13 12 13
ans = 13×16
0 0 0 0 0 0 0 0 0 0 0 1 7 13 14 13 0 0 0 0 0 0 0 0 0 0 0 2 10 13 14 13 14 11 6 6 7 7 6 7 4 12 12 13 14 13 15 14 14 11 6 6 7 7 6 7 4 12 12 13 14 13 15 14 13 13 14 14 14 14 13 12 13 14 13 14 14 13 12 12 13 13 14 14 14 14 13 12 13 14 13 14 14 13 12 12 12 12 12 9 11 7 12 14 15 15 13 9 9 9 9 9 12 12 12 9 11 7 12 14 15 15 13 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 14 13 13 9 9 9 9 9 9 9 9 9 9 9 9 9 14 13 13
ans = 58×16
1 7 12 13 11 12 6 2 8 6 4 2 6 2 6 0 1 7 12 13 11 12 6 2 8 6 4 2 6 2 6 0 0 0 0 0 7 7 0 2 0 3 4 0 7 5 1 0 1 0 0 0 7 7 1 0 5 0 4 0 5 5 1 0 7 5 2 7 7 0 1 4 4 4 1 7 7 1 0 0 7 5 2 7 7 0 1 4 4 4 1 7 7 1 0 0 6 5 1 6 7 2 0 6 4 1 7 7 2 1 7 4 6 5 1 6 7 2 0 6 4 1 7 7 2 1 7 4 5 0 3 7 1 0 7 4 1 2 7 7 1 1 8 2 5 0 3 7 1 3 7 6 0 7 5 7 1 0 6 3

更多回答（1 个）

KSSV
KSSV 2021-6-2
id = zeros([],1) ; % indices of required strings
count = 0;
for i = 1:size(m,1)
t = str2num(m(i,:)) ;
if any(t)
count = count+1 ;
id(count) = i ;
end
end
iwant = m(id,:)

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