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From: Kris zenitis on 27 Apr 2010 17:11
Hello to everybody i ve stuck the the following simple problem and i need help. I have got a simple loop:

for i=1:n
if dec_values(i)>0
x(i,1)=mod(i,262);
y(i,1)=mod(i,442);
end
end

Where the dec_values is a 114000x1 table. I want the x,y to have the calculation of the mod only when i satisfy the statement dec_values(i)>0 .

For example when i run this code x finally is a 114000x1 table but the dimension i want is sth like kx1 where k is the sum of how much i satisfy the statement.

Any help???
From: Nathan on 27 Apr 2010 17:15
On Apr 27, 2:11 pm, "Kris zenitis" <gio.1...(a)hotmai.com> wrote:
> Hello to everybody i ve stuck the the following simple problem and i need help. I have got a simple loop:
>
>     for i=1:n
>         if dec_values(i)>0  
>             x(i,1)=mod(i,262);
>             y(i,1)=mod(i,442);
>         end
>     end
>
> Where the dec_values is a 114000x1 table. I want the x,y to have the calculation of the  mod only when i satisfy the statement dec_values(i)>0 .
>
> For example when i run this code x finally is a 114000x1 table but the dimension i want is sth like kx1 where k is the sum of how much i satisfy the statement.
>
> Any help???

You will need a separate counting variable then. Let's use k, since
you mentioned it.
k = 1;
for i=1:n
if dec_values(i)>0
x(k,1)=mod(i,262);
y(k,1)=mod(i,442);
k=k+1;
end
end


-Nathan
From: Kris zenitis on 27 Apr 2010 17:27
Nathan thanks a lot for your help but the problem is the same x,y are taking all the i from 1to115000 x=mod(1,262),x=mod(2,262),x=mod(3,262),...,x=mod(115000,262). I dont understand why "if" doesnt work as i wanted.
From: Matt Fig on 27 Apr 2010 17:47
Perhaps you didn't clear out your old x and y? Nathan's solution does what you described. We assume n is the length of dec_values:

clear all
n = 20;
dec_values = round(rand(n,1)*20)-round(rand(n,1)*20);
k = 1;
for ii=1:n
if dec_values(ii)>0
x(k,1)=mod(ii,262);
y(k,1)=mod(ii,442);
k=k+1;
end
end

% A vectorized approach.
idx = find(dec_values>0);
x2 = mod(idx,262);
y2 = mod(idx,442);

isequal(x,x2)
isequal(y,y2)
From: Kris zenitis on 27 Apr 2010 18:38
basically ok you have right it works. My problem is that i want x,y to have positive numbers so I include in the for loop one if

for i=1:n
if dec_values(i)>0
x=mod(i,262);
y=mod(i,442);

if x>0 & y>0
xx(k,1)=x;
yy(k,1)=y;
end
k=k+1;
end

But afterthat i still had some zeros in the yy table.
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