Prev: How to divide a line in equal section?
Next: Fix for Isosurface problems
From: Sydney Hai on 16 Jun 2010 15:26
Hi all,

I have been troubled with this problem using for loop, hope I can get some help.

I am trying to modify a text file with columns of strings and numeric values.
Here I am extracting XYZ coordinates from a file and then do calculation with all 64 rows of XYZ and find out the four smallest distances from A(X,Y,Z) to B(X1,Y1,Z1)

i used
for v=1:64
fid=fopen('FILE_Si.m');
C=textscan(fid, '%*s %*s %f %f %f %*[^\n]', 64);
X=C{1,1}(v);
Y=C{1,2}(v);
Z=C{1,3}(v);
end
to read the coordinates in the file, X, Y, and Z for all 64 rows of the file.
first of all, is there a way to save the XYZ values I get in the loop to excel or something so I don't end up with only one value in the end? because each new value overwrites the previous one.
I tried saving all the variables, but then I wouldn't be able to do calculations with all of those or sort them cuz of the variable names.

Then I thought I could do the calculation in the for loop, so when doing the calculation of the distance of this point with another point (X1,Y1,Z1), i used
distance=sqrt((X-X1)^2+(Y-Y1)^2+(Z-Z1)^2;
i wish to have all the distances from the 64 calculations so I can sort them in the end to get the four smallest distance values.
I did [B, IX]=sort(distance); so once I get the smallest value I'll be able to know the index of the XYZ of that min distance.
but B only contains one value so the sorting is not working.

One last question is, can I set a condition in for loop, that when the A (X, Y, Z) value is the same as C(X2,Y2,Z2), eliminate that A point in the for loop data and the rest of the calculation?
I tried, for v=1:64, if v=h(my C point), break, end;
but it wouldn't work.

any idea how I can solve these problems? It's been troubling me for days, thank you all so much!

Best,
Sydney
From: us on 16 Jun 2010 15:46
"Sydney Hai" <xueyinghai(a)gmail.com> wrote in message <hvb8gs$jt7$1(a)fred.mathworks.com>...
> Hi all,
>
> I have been troubled with this problem using for loop, hope I can get some help.
>
> I am trying to modify a text file with columns of strings and numeric values.
> Here I am extracting XYZ coordinates from a file and then do calculation with all 64 rows of XYZ and find out the four smallest distances from A(X,Y,Z) to B(X1,Y1,Z1)
>
> i used
> for v=1:64
> fid=fopen('FILE_Si.m');
> C=textscan(fid, '%*s %*s %f %f %f %*[^\n]', 64);
> X=C{1,1}(v);
> Y=C{1,2}(v);
> Z=C{1,3}(v);
> end
> to read the coordinates in the file, X, Y, and Z for all 64 rows of the file.
> first of all, is there a way to save the XYZ values I get in the loop to excel or something so I don't end up with only one value in the end? because each new value overwrites the previous one.
> I tried saving all the variables, but then I wouldn't be able to do calculations with all of those or sort them cuz of the variable names.
>
> Then I thought I could do the calculation in the for loop, so when doing the calculation of the distance of this point with another point (X1,Y1,Z1), i used
> distance=sqrt((X-X1)^2+(Y-Y1)^2+(Z-Z1)^2;
> i wish to have all the distances from the 64 calculations so I can sort them in the end to get the four smallest distance values.
> I did [B, IX]=sort(distance); so once I get the smallest value I'll be able to know the index of the XYZ of that min distance.
> but B only contains one value so the sorting is not working.
>
> One last question is, can I set a condition in for loop, that when the A (X, Y, Z) value is the same as C(X2,Y2,Z2), eliminate that A point in the for loop data and the rest of the calculation?
> I tried, for v=1:64, if v=h(my C point), break, end;
> but it wouldn't work.
>
> any idea how I can solve these problems? It's been troubling me for days, thank you all so much!
>
> Best,
> Sydney

this is awkward...
a hint:
- read the content of your file at once into row-vecs X/Y/Z...
- then compute your distance profile...
- and save your results using

help xlswrite;

us
From: Sydney Hai on 16 Jun 2010 16:09
"us " <us(a)neurol.unizh.ch> wrote in message <hvb9ls$3ms$1(a)fred.mathworks.com>...
> "Sydney Hai" <xueyinghai(a)gmail.com> wrote in message <hvb8gs$jt7$1(a)fred.mathworks.com>...
> > Hi all,
> >
> > I have been troubled with this problem using for loop, hope I can get some help.
> >
> > I am trying to modify a text file with columns of strings and numeric values.
> > Here I am extracting XYZ coordinates from a file and then do calculation with all 64 rows of XYZ and find out the four smallest distances from A(X,Y,Z) to B(X1,Y1,Z1)
> >
> > i used
> > for v=1:64
> > fid=fopen('FILE_Si.m');
> > C=textscan(fid, '%*s %*s %f %f %f %*[^\n]', 64);
> > X=C{1,1}(v);
> > Y=C{1,2}(v);
> > Z=C{1,3}(v);
> > end
> > to read the coordinates in the file, X, Y, and Z for all 64 rows of the file.
> > first of all, is there a way to save the XYZ values I get in the loop to excel or something so I don't end up with only one value in the end? because each new value overwrites the previous one.
> > I tried saving all the variables, but then I wouldn't be able to do calculations with all of those or sort them cuz of the variable names.
> >
> > Then I thought I could do the calculation in the for loop, so when doing the calculation of the distance of this point with another point (X1,Y1,Z1), i used
> > distance=sqrt((X-X1)^2+(Y-Y1)^2+(Z-Z1)^2;
> > i wish to have all the distances from the 64 calculations so I can sort them in the end to get the four smallest distance values.
> > I did [B, IX]=sort(distance); so once I get the smallest value I'll be able to know the index of the XYZ of that min distance.
> > but B only contains one value so the sorting is not working.
> >
> > One last question is, can I set a condition in for loop, that when the A (X, Y, Z) value is the same as C(X2,Y2,Z2), eliminate that A point in the for loop data and the rest of the calculation?
> > I tried, for v=1:64, if v=h(my C point), break, end;
> > but it wouldn't work.
> >
> > any idea how I can solve these problems? It's been troubling me for days, thank you all so much!
> >
> > Best,
> > Sydney
>
> this is awkward...
> a hint:
> - read the content of your file at once into row-vecs X/Y/Z...
> - then compute your distance profile...
> - and save your results using
>
> help xlswrite;
>
> us

Hi,

Thanks so much for the prompt reply!
One question, I'm calculating the distance of one point with all the 63 others, would i be able to do that without a for loop? or how can i save all the distance results and then sort?

I appreciate it!
Sydney
From: us on 16 Jun 2010 16:19
"Sydney Hai"
> One question, I'm calculating the distance of one point with all the 63 others, would i be able to do that without a for loop? or how can i save all the distance results and then sort?
>
> I appreciate it!
> Sydney

one of the solutions

% the data
x=[0,1,4,6,-1];
y=[0,1,2,2,2];
x0=0;
y0=0;
% the engine
d2=(x-x0).^2+(y-y0).^2; % <- use this if you only want to sort, etc...
d=sqrt(d2); % <- use this to get the actual distance...

us
From: dpb on 16 Jun 2010 16:26
Sydney Hai wrote:
....

> Thanks so much for the prompt reply! One question, I'm calculating the
> distance of one point with all the 63 others, ...

Is that 63 distances from a selected point or the combination of all
possible distances between the full vector of 63 locations?

--
 |  Next  |  Last
Pages: 1 2
Prev: How to divide a line in equal section?
Next: Fix for Isosurface problems