I have trouble with cell arrays

2014 10 9
2 个回答
更新时间：2014 10 9
2 次查看（30 天）

0 个投票

I currently have a 1x4 cell array where each of the four elements is a 134x1 array of different data types. The cell array was created from a text file by a textscan call. What I wanted is a 134x4 cell array. How do I get there?

1 个评论
显示 -1更早的评论 隐藏 -1更早的评论

José-Luis
José-Luis 2014-10-9
Well, a solution is not to use textscan() but a lower level routine like sscanf() that will allow you to specify formats for all elements.

请先登录，再进行评论。

请先登录，再回答此问题。

回答（2 个）

Adam
Adam 2014-10-9

1 个投票

res = C{:};
where C is your cell array would work in this case.

5 个评论
显示 3更早的评论 隐藏 3更早的评论

David
David 2014-10-9
Sorry, but that doesnt work...
a = single(ones(4,1));
b = double(zeros(4,1));
c = {a b};
c2 = c{:};
c2 =
1
1
1
1
Adam
Adam 2014-10-9
Ah, sorry, I missed the "different data types" part of the question and read it as you wanting a standard array.
Adam
Adam 2014-10-9
num2cell([c{:}])
I think is what is needed to get the cell array result.
David
David 2014-10-9
That works for the simple example. My actuall cell contains character arrays too though. Is there a more universal way that can handle char and numerical data types?

请先登录，再进行评论。

Andrew Reibold
Andrew Reibold 2014-10-9
编辑：Andrew Reibold 2014-10-9

0 个投票

Is this what you are looking for?
a = {0 0 0 0};
b = {1 1 1 1};
c = {'1' '2' '3' '4'};
d = {'look,';'this';'has';'characters!'};
MyBigCell = {a{:}; b{:}; c{:}; d{:}} % <-- Try this with your cells
Output:
MyBigCell =
[ 0] [ 0] [ 0] [ 0]
[ 1] [ 1] [ 1] [ 1]
'1' '2' '3' '4'
'look,' 'this' 'has' 'characters!'

10 个评论
显示 8更早的评论 隐藏 8更早的评论

David
David 2014-10-9
编辑：David 2014-10-9
The cell contents are not cells themseleves, but arrays. I'll try and be more discriptive without giving away propriatary data...
a = single(ones(4,1));
b = double(zeros(4,1));
c = ['fast';'slow';'four';'five';];
d = true(4,1);
badcell = {a(:) b(:) c(:) d(:)}
small_example_of_cell_I_want_without_having_to_type_536_values_or_use_convoluted_for_loops = {1 0 'fast' true;
1 0 'slow' true;
1 0 'four' true;
1 0 'five' true;}
Output:
badcell =
[4x1 single] [4x1 double] [16x1 char] [4x1 logical]
small_example_of_cell_I_want_without_having_to_type_536_values_ =
[1] [0] 'fast' [1]
[1] [0] 'slow' [1]
[1] [0] 'four' [1]
[1] [0] 'five' [1]
Andrew Reibold
Andrew Reibold 2014-10-9
编辑：Andrew Reibold 2014-10-9
Convert Character array to cell using cellstr.
Convert the logical array to cell using num2cell
If there is too many to do by hand, write loops to check class and do such :)
a = {0 0 0 0}
b = {1 1 1 1}
c = ['fast'; 'slow'; 'four'; 'five']
d = true(1,4)
c2 = cellstr(c)
c = c2'
d = num2cell(d)
MyCell = {a{:}; b{:}; c2{:}; d{:}}
MyCell =
[ 0] [ 0] [ 0] [ 0]
[ 1] [ 1] [ 1] [ 1]
'fast' 'slow' 'four' 'five'
[ 1] [ 1] [ 1] [ 1]
EDIT: Just noticed my final answer was transposed from what you wanted haha. Here
MyCell'=
[0] [1] 'fast' [1]
[0] [1] 'slow' [1]
[0] [1] 'four' [1]
[0] [1] 'five' [1]
David
David 2014-10-9
编辑：David 2014-10-9
yea... thats aparent, but I'd rather not convert the arrays to cell arrays only to turn them back to differently organized arrays in a bigger cell array. I've got hundreds, soon to be thousands, of data sets to do this to. Otherwise I would just open this up in excell. I'm looking for something more low level and efficient.
edit:
some elaboration... unless I am missing something about indexing into cells, I would even have to extract the arrays from the cells, convert them into individual cells, and then recreate the cell I want.
Andrew Reibold
Andrew Reibold 2014-10-9
编辑：Andrew Reibold 2014-10-9
The great part about scripting is that you really only have to do it one time no matter how many sets you have.
Good luck!
David
David 2014-10-9
The bad part about inefficient scripting is that I leave the program running overnight and it's still not done in the morning. Matlab is suposed to be built to handle TONS of data efficiently. I don't want to sacrifice that because a human can't read:
badcell =
[4x1 single] [4x1 double] [16x1 char] [4x1 logical]
Andrew Reibold
Andrew Reibold 2014-10-9
编辑：Andrew Reibold 2014-10-9
Last overnight and not be done?
I just ran a test case using larger arrays than yours (144 rather than 134) 1000 times in 30 seconds.
Is the problem related to a human's ability to read.. or is it really related to the ability to code? ;)
jk jk. I dont know how to help bud, I'm sorry. Thought I had a solution.
David
David 2014-10-9
This is a one part of a big program. I've got to pull data off of the archive onto a local drive, import it into matlab, organize it into channels, search for anomolies, output it to something a human can read, and move on to the next file. Reguardless of how fast of a computer my IT department thinks is sufficient, I want to find an efficient way of doing this. The mathworks guy who trained me a few years ago stressed how inefficient changing types is, and that if you are using a for loop, there is probably a better way.
José-Luis
José-Luis 2014-10-9
编辑：José-Luis 2014-10-9
Matlab is NOT built to handle tons of data efficiently. If you want to handle large amounts of data then you should use a database.
Processor speed is unlikely to be the bottleneck when handling large datasets. Available memory is more likely to be the culprit.
David
David 2014-10-9
...perhaps I should have said process tons of data efficiently.
José-Luis
José-Luis 2014-10-9
编辑：José-Luis 2014-10-9
Well, then you could start by not using textscan() but the faster sscanf().
Even faster would be to use a binary format to store your data instead of text. Of course, IO becomes more complicated then.
And if I'm going to be nitpicking, as much as I love Matlab, it is not the best tool to run things fast, but it's one of the better ones to write code fast.
JIT and whatnot, an overhead is an overhead.

请先登录，再进行评论。

类别

在 帮助中心 和 File Exchange 中查找有关 Matrix Indexing 的更多信息

产品

标签

提问:

David
David
2014-10-9

编辑：

José-Luis
José-Luis
2014-10-9

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by