How not to repeat values in array using matlab / octave

问题

Thanks goes out to Shai for getting my code to be much more efficient. The link to the original thread is here. Original Thread

How can I have a loop check and stop if a number in the "array_all" array has been repeated from the "x" array.

Example:

Here's the code below:

x=[9,8,7,6,5,4,3,2,1]
array_all = bsxfun( @times, x(:), [1 .5 .25] ) %// generate for all values 

eq_ = bsxfun( @eq, array_all, permute( x(:), [3 2 1] ) );
eq_ = max( eq_, [], 2 ); %// we do not care at which column of array_all x appeared
[mx firstRowToAppearIn] = max( squeeze(eq_), [], 1 ); 

toBePruned = 1:numel(x) > firstRowToAppearIn; %// prune elements that appear in array_all in a row preceding their location in x
pruned_array=array_all;
pruned_array(toBePruned,:) = []; %// remove those lines

st = struct();
for ii=1:size(pruned_array,1)
    nm = sprintf('array_dyn_name%d',ii);
    st.(nm) =pruned_array(ii,:);
end
pruned_array
fprintf('\nfinally Done-elapsed time -%4.4fsec- or -%4.4fmins- or -%4.4fhours-\n',toc,toc/60,toc/3600);

The output is:

array_all =

   9.00000   4.50000   2.25000
   8.00000   4.00000   2.00000
   7.00000   3.50000   1.75000
   6.00000   3.00000   1.50000
   5.00000   2.50000   1.25000
   4.00000   2.00000   1.00000
   3.00000   1.50000   0.75000
   2.00000   1.00000   0.50000
   1.00000   0.50000   0.25000

pruned_array =

   9.0000   4.5000   2.2500
   8.0000   4.0000   2.0000
   7.0000   3.5000   1.7500
   6.0000   3.0000   1.5000
   5.0000   2.5000   1.2500

We run into problems with 1.0000 0.5000 0.2500 we know it's due to the fact that it found the number 1.0000 in a previous check of the array array_all but how can we fix it?

The array we are trying to get is below:

pruned_array =

   9.0000   4.5000   2.2500
   8.0000   4.0000   2.0000
   7.0000   3.5000   1.7500
   6.0000   3.0000   1.5000
   5.0000   2.5000   1.2500
   1.0000   0.5000   0.2500

PS: The numbers will not be this simple there will be thousands of values. And I won't know when they will repeat.

Ps: I'm using octave 3.8.1

回答1:

Using a loop

%// create the data
x=[9,8,7,6,5,4,3,2,1]
array_all = bsxfun( @times, x(:), [1 .5 .25] );

Start pruning

n = numel(x);
valid = false(n,1); %// at first, only first line is valid
valid(1) = true;
for ii=2:n, %// first line is valid by default
    valid(ii) = ~any( reshape( array_all( valid, : ),[],1) == x(ii) );
end

Now leave only valid entries

array_all = array_all(valid, : );

You can try this out at ideone.

来源：https://stackoverflow.com/questions/28280544/how-not-to-repeat-values-in-array-using-matlab-octave

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arrays

matlab

octave