indices and values

2011 11 22
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HI,
If I have this txt file(indices and values),and need read it into array without using for loop. Is there command do that?
(1,2) 3
(2,3) 4
thanks

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huda nawaf
huda nawaf 2011-11-22
sorry ,I were not clear.
I mean a command place each element in it's index
where the above file be :
0 3 0
0 0 4

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回答（3 个）

Walter Roberson
Walter Roberson 2011-11-22

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textscan(fid, '%*c%f%*c%f%*c%f')

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Walter Roberson
Walter Roberson 2011-11-22
c = textscan(fid, '%*c%f%*c%f%*c%f');
sparse(c{1},c{2},c{3})
Walter Roberson
Walter Roberson 2011-11-22
c = textscan(fid, '%*c%f%*c%f%*c%f');
accumarray([c{1},c{2}], c{3})
huda nawaf
huda nawaf 2011-11-23
thanks ,
it is perfect command. but unfortunately,the same problem.
if there is no way,then I have to add RAM to my computer.
Look:
fid = fopen('d:\matlab7\work\flixsterdata\finalflix0.txt','r');
>> c = textscan(fid, '(%d,%d)\t%d');
>> c1=double(c{1});
>> c2=double(c{2});
>> c3=double(c{3});
>> w=double(c1); w1=double(c2); w2=double(c3);
>> a=accumarray([w,w1],w2);
??? Error using ==> accumarray
Out of memory. Type HELP MEMORY for your options.
Walter Roberson
Walter Roberson 2011-11-23
How much RAM and swap space are you configured for now?
You are using the MATLAB Student Version, aren't you? Those are officially only the 32 bit versions, so if you cannot configure enough RAM and swap space in your existing system, then you will not be able to read larger files by getting more RAM.
Have you considered splitting your files in to even smaller pieces?
I have completely lost track of what you intend to do with the arrays once you have read them in?
Andrei Bobrov
Andrei Bobrov 2011-11-23
a = accumarray([w,w1],w2,[],[],[],true)
Walter Roberson
Walter Roberson 2011-11-23
Interesting, Andrei; I had quite forgotten that flag.
I am, however, not convinced at the moment that the array really is sparse; Huda earlier (in a different Question on this same topic) made reference to the array indices being sequential.

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Fangjun Jiang
Fangjun Jiang 2011-11-22

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[I,J,V]=textread('test.txt','(%f,%f) %f');
A=zeros(2,3);
A(sub2ind(size(A),I,J))=V
Andrei Bobrov
Andrei Bobrov 2011-11-23

0 个投票

[EDIT]
fid = fopen('nameyourfile.txt','r');
c = textscan(fid, '(%f,%f)%f','collectoutput',true);
fclose(fid)
a = accumarray(c{1}(:,1:2),c{1}(:,3),[],[],[],true)
[ADD] 22:32MSD
fid = fopen('nameyourfile.txt','r');
c1 = textscan(fid, '(%f,%f)%f');
fclose(fid);
a = sparse(c1{:});

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huda nawaf
huda nawaf 2011-11-23
I got this error when ran it:
??? Function 'accumarray' is not defined for values of class 'int32'.
Error in ==> accumarray at 73
[varargout{1:nargout}] = builtin('accumarray', varargin{:});
huda nawaf
huda nawaf 2011-11-23
I got this error when use cellfun
c = cellfun(@(x)double(x),c,'un',0);
??? Too many inputs.

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huda nawaf
huda nawaf
2011-11-22

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