Converting entire cell array to strings
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x={'words',10,20,30,'more words'}
How do I convert the entire cell array above to strings?
2 个评论
Image Analyst
2015-6-3
x{1} and x{5} are already strings. Do you want to scan the cell array and convert the cells that have numbers in them to strings? Or do you want 5 separate string variables, like x1, x2, x3, x4, and x5?
x1 = x{1}
x2 = num2str(x{2});
x3 = num2str(x{3});
x4 = num2str(x{4});
x5 = x{5};
采纳的回答
Azzi Abdelmalek
2015-6-3
x={'words',10,20,30,'more words'}
out=cellfun(@num2str,x,'un',0)
2 个评论
It works because num2str just return the string unchanged when given a string.
edit: As pointed out by per, this relies on the undocumented and actually unexpected behaviour of num2str. Such code could break in the future. (But mathworks also often breaks documented behaviour)
Rainer
2015-6-3
更多回答（1 个）
per isakson
2015-6-3
is this close to what you want?
>> strsplit( strjoin(x), ',')
ans =
'words' '10' '20' '30' 'more words'
7 个评论
Rainer
2015-6-3
per isakson
2015-6-3
编辑：per isakson
2015-6-3
On R2013a it works
>> version
ans =
8.1.0.604 (R2013a)
>> x={17,'words',10,20,30,'more words'}
x =
[17] 'words' [10] [20] [30] 'more words'
>> strsplit( strjoin(x), ',' )
ans =
'17' 'words' '10' '20' '30' 'more words'
but not on R2014a
>> version
ans =
8.3.0.532 (R2014a)
>> x={17,'words',10,20,30,'more words'}
strsplit( strjoin(x), ',' )
x =
[17] 'words' [10] [20] [30] 'more words'
Error using strjoin (line 52)
First input must be a 1xN cell array of strings.
Maybe that is too "smart" and was removed
Guillaume
2015-6-4
I'd say it's a good thing it's not behaving like that anymore as I would not expect a string joining function to also perform numeric to string conversion. Feature creep and all that...
per isakson
2015-6-4
Indeed that is a good thing. However, I find it worrying that this "feature" was deliberately included in the first place. Especially since strjoin is a fairly recent function.
per isakson
2015-6-4
编辑：per isakson
2015-6-4
The solution with num2str relies on the undocumented (AFAIK) feature that a string input is returned as output.
And I don't find a suitable words to comment on
>> num2str('ten')
ans =
ten
>> int2str('ten')
ans =
116 101 110
Guillaume
2015-6-5
You're right the behaviour of num2str with string inputs is not documented and kind of unexpected. If num2str adhered to its documentation it should throw an error when passed a string. Sloppy coding or sloppy documenting.
Perhaps matlab should have a ToString function like java and .Net.
The behaviour of int2str makes sense to me. It's equivalent to
num2str(uint16('ten'));
per isakson
2015-6-5
编辑：per isakson
2015-6-5
It doesn't help the beginner, me included, that the two functions, num2str and int2str handle string inputs differently.
Yes, "the behavior of int2str makes sense" and that's because it dates back to the beginning of Matlab when everything was numerical arrays. A string was just another way to interpret the array. (My mental model.) By the way, I use strfind to search for sequences of whole numbers in double arrays. I think of that as "us' trick".
However, this behavior of int2str is not documented(?)
There are a number of fundamental function, which converts strings to vectors of ascii-numbers. That is not explicitly stated in the documentation(?)
>> real('ten')
ans =
116 101 110
>> uint16('ten')
ans =
116 101 110
Enough ranting for now!
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