indices and values

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

[huda nawaf]

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

Answer 1

[Walter Roberson]

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

[Walter Roberson]

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

sparse(c{1},c{2},c{3})

[Walter Roberson]

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

accumarray([c{1},c{2}], c{3})

[huda nawaf]

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]

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]

a = accumarray([w,w1],w2,[],[],[],true)

[Walter Roberson]

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.

Answer 2

[Fangjun Jiang]

[I,J,V]=textread('test.txt','(%f,%f) %f');
A=zeros(2,3);
A(sub2ind(size(A),I,J))=V

Answer 3

[Andrei Bobrov]

[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{:});

[huda nawaf]

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]

I got this error when use cellfun

c = cellfun(@(x)double(x),c,'un',0);

??? Too many inputs.