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how to horizontally concatenate two strings, being one a cell array and the other a num2str converted gpuarray?

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Isabel
Isabel 2017-8-21
编辑： Stephen23 2017-8-24
Hello there, I am trying to concatenate two strings, but I'm missing something. The idea is to get these strings:
'CELL:0.1,CELLA:0.2,CHAR:0.3,GCH4:0.4,GH2:0.5'
'CELL:0.1,CELLA:0.3,CHAR:0.5,GCH4:0.7,GH2:0.9'
but my output is:
composition =
CELL:,CELLA:,CHAR:,GCH4:,GH2:0.1 0.2 0.3 0.4 0.5
composition =
CELL:,CELLA:,CHAR:,GCH4:,GH2:0.1 0.3 0.5 0.7 0.9
My code is below. Any help will be much appreciated. Thank you!
A1 = 0.1:0.1:0.5;
A2 = 0.1:0.2:1;
A1 = gpuArray(A1);
A2 = gpuArray(A2);
A = [A1;A2];
C = ['CELL:',',CELLA:',',CHAR:',',GCH4:',',GH2:'];
for i = 1:2
sp = sprintf('%s',C);
y_sp = sprintf('%s',num2str(A(i,:)));
composition = strcat(sp,y_sp);
display(composition);
end

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采纳的回答

Isabel
Isabel 2017-8-24
To whom it might concern I found the solution:
C = 'CELL:%.4f,CELLA:%.4f,CHAR:%.4f,GCH4:%.4f,GH2:%.4f';
for i = 1:2
composition{i} = sprintf(C,(A(i,1:a)));
composition{i} = num2str(composition{i});
end
  2 个评论
Stephen23
Stephen23 2017-8-24
编辑：Stephen23 2017-8-24
You could very easily make your code adjust automatically for different sizes of A and C, and to automatically generate the sprint format string as well:
A = [0.1:0.1:0.5;0.1:0.2:1]
C = {'CELL','CELLA','CHAR','GCH4','GH2'};
%
fmt = sprintf(',%s:%%.4f',C{:});
fmt = fmt(2:end);
N = size(A,1);
Z = cell(N,1);
for k = 1:N
Z{k} = sprintf(fmt,A(k,:));
end
Note how I preallocated the output cell array, which for a small array like this might not be strictly necessary, but is a good habit to learn.

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更多回答（2 个）

Adam
Adam 2017-8-21
编辑：Adam 2017-8-21
If you define C as a cell array instead then, for example, this should work:
C = { 'CELL:',',CELLA:',',CHAR:',',GCH4:',',GH2:' }
cell2mat( reshape( [C; arrayfun( @num2str, A1, 'UniformOutput', false )], [1 10] ) )
In a char array all your components just get merged into one long char that is much more complicated to extract the components from to concatenate each one with an element of A1
  11 个评论
显示 9更早的评论
José-Luis
José-Luis 2017-8-22
That is fair enough. I like Matlab myself: Wouldn't be answering here otherwise.
If you want down to the metal performance, then it might not be the best choice. Because of this, C++ is my language of choice these days when I ---really--- need fast. Cost is also a problem: since University days, I haven't had an employer willing to shell out for all the toolboxes it'd be neat to have.
That's why, based on the kind of problem they have, I keep recommending people to look in other places as there are better (and possibly free) tools out there.
That being said, I do agree with you: slow code will be slow, be it in assembly or Matlab.

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Andrei Bobrov
Andrei Bobrov 2017-8-21
C = { 'CELL:','CELLA:','CHAR:','GCH4:','GH2:' }
S = string(C) + [.1:.1:.5;.1:.2:.9]
out = join(S,',');
  2 个评论
Walter Roberson
Walter Roberson 2017-8-21
The above requires R2016b or later.
With R2017a or later, the above could also be coded as
C = [ "CELL:", "CELLA:", "CHAR:", "GCH4:','GH2:" ];
S = C + [.1:.1:.5;.1:.2:.9]
out = join(S,',');
Unfortunately both version of this will fail when the numeric array is a gpuArray :(

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