Creating a cell array of size n
显示 更早的评论
I need a cell array of size n, like if n is 3, I need
C = {'red','red','red'}
If n is 100,
C = {'red','red',.......'red'}(100 cells)
I tried this,
C = cell(1,n);
for i = 1:n
C(i) = 'red';
end
This gives known error of conversion to cell from char is not possible.
采纳的回答
James Tursa
2012-7-5
编辑：James Tursa
2012-7-5
The most memory efficient way is the following without a loop:
C(1:n) = {'red'}; % Assuming C doesn't exist yet (EDITED)
That is because in the above line, all n copies of the 'red' string are reference copies of each other (like a shared data copy), so the memory footprint is smaller than filling each cell individually with a brand new allocated string in a loop.
Having said that, I strongly suspect that what you are attempting to do is futile. If you change any of the individual 'red' strings downstream in your code you will probably need to allocate brand new cell element variables anyway, so this pre-allocation of 'red' would be useless (actually wastes time) regardless of the methoud you use to create C in the first place (my method or with a loop). The only exceptions would be if you don't plan on altering C at all downstream, or if you plan to operate on each string "in-place" ... i.e., changing the contents of the string directly without changing its length, etc. Can you elaborate on what you intend to do with C downstream in your code?
4 个评论
Kye Taylor
2012-7-5
The command C(1,n) = {'red} only assigns the cell {'red'} to the nth element of C. The jth elements (for j < n) are empty arrays... NOT referenced copies of the nth element.
James Tursa
2012-7-5
编辑：James Tursa
2012-7-5
My typo. Should have been:
C(1:n) = {'red'}
I have edited my original post. All of my original comments still apply.
Albert Yam
2012-7-5
See Jan Simon's answer. James just missed a '1:n'.
C(1,1:n) = {'red'};
James Tursa
2012-7-5
P.S. My comments also apply to Jan's answer, since it essentially does the same thing.
更多回答（3 个）
Jan
2012-7-5
C = cell(1, n);
C(:) = {'red'};
F.
2012-7-5
Your error :
C(i) = 'red';
C is a cell array, with C(i) you reach the place in the cell array and not the element which is in this place. So try :
C{i} = 'red';
2 个评论
F.
2012-7-5
I'm not sure but try also this :
n = 100
repmat( {'red'}, 1, n )
Giuseppe Degan Di Dieco
2021-5-19
Dear F,
thanks for your explanation of the cell array object.
Actually, it was quite tricky to understand.
Best.
grapevine
2012-7-5
You have to modify your code in this way :
C = cell(1,n);
for i = 1:n
C(i) = java.lang.String('red');
end
Another solution could pass by using the function: char2cell, which is available on Matlab Central Exchange
good luck
类别
在 帮助中心 和 File Exchange 中查找有关 Matrix Indexing 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
