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Remove for-loop by using cellfun

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Christophe
Christophe 2014-7-3
编辑： James Tursa 2014-7-3
var_name = {'A','B','C'};
for i=1:length(var_name)
eval([cell2mat(var_names(i)) '=zeros(10,1);'])
end
How can I do?
Thanks in advance
  3 个评论
显示 1更早的评论
Christophe
Christophe 2014-7-3
The objective is to make preallocation for about 106 variable (which are double).
Cedric
Cedric 2014-7-3
编辑：Cedric 2014-7-3
If all "variables" contents are 10x1 numeric arrays, it would be much more natural/efficient (and simpler) to build an array of zeros. For 3 "variables", for example:
nData = 3 ;
data = zeros( 10, nData ) ;
and then use e.g.
data(:,2) = ...
to get the column vector for the second data.

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采纳的回答

James Tursa
James Tursa 2014-7-3
编辑：James Tursa 2014-7-3
You can't avoid the for loop. Either it will be explicitly in your code, or whatever MATLAB function you use will have it in the background. It isn't a big deal in your case, so I would just advise keeping it explicit. Makes your code more readable anyway. E.g.,
z = zeros(10,1);
for i=1:length(var_name)
eval([var_names{i} '=z;'])
end
The reason for doing the "z = zeros(10,1)" up front is to create shared data copies of the 10x1 zeros matrix instead of individual ones. For you small example (106 variables) it won't make any practical difference in timing, but I thought I would include this option just for completeness of the example.

更多回答（3 个）

Robert Cumming
Robert Cumming 2014-7-3
Create the dynamic variables inside a struct instead of using eval
var_name = {'A','B','C'};
for i=1:length(var_name)
myStruct.(var_name{i}) = zeros(10,1);
end
the cyclist
the cyclist 2014-7-3
I suggest you read this document for some suggestions.
the cyclist
the cyclist 2014-7-3
编辑：John D'Errico 2014-7-3
Please tell us you are not naming those 106 variables A,B,C, ..., AA, AB, AC, etc!
Could you do this via a cell array instead?
for n = 1:106
A{n} = zeros(10,1);
end
and use those as your variables?
  2 个评论
Christophe
Christophe 2014-7-3
I'm not naming these variables A, B, C ... Variables names have already been defined by another user. These varaibles names are linked to another software (AMESIM from Siemens/LMS) & here is few examples: injector_delay, mass_fuel ... I want to use vectorization to avoid for-loop & I think we can use cell2fun but I don't know how to
John D'Errico
John D'Errico 2014-7-3
Changed zeros{10,1} to zeros(10,1).

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