3D plot or surf plot problem

Hello all,

I have a problem, trying to solve it for the last two days, but could not succeed. ANY HELP WOULD BE GREATLY APPRECIATED.

I have a data in txt file called 'ecoli'. The first column and first row are wavelength parameters.

The rest of the matrix contains intensity values.

here is what i have done. I have deleted first element in first column and row because it was a X/Y text parameter.

Then i have reduced matrix by deleting first column and row, to get the rest of the intensity value matrix.

 X=ecoli(:,1);
>> Y=ecoli(1,:);
>> ind=[1]

ind =

     1

>> X(ind)=[]; >> Y(ind)=[]; >> ecoli(:,1)=[]; >> ecoli(1,:)=[]; >> Z=ecoli; >> plot3(X,Y,Z);

Download link for text file is https://rapidshare.com/files/460746782/ecoli.txt

alternatively try here http://www.filefactory.com/file/cb2a267/n/ecoli.txt

I get this error.

??? Error using ==> plot3 Vectors must be the same lengths.

Could somebody through some light on this problem. I know some where the lengths of vectors are not same thats y i could not plot.

Thanks

Answer 1

[Sean de Wolski]

Ecoli - fun stuff

size(X)
size(Y)
size(Z)

which one is different and why?

[VISWANATH]

> size(X)

ans =

381 1

>> size(Y)

ans =

1 77

>> size(Z)

ans =

381 77

looks like i need to make X,Y into a matrix then plot. Is that correct?

[Matt Fig]

surf(repmat(X,1,77),repamt(Y,381,1),Z)

[Sean de Wolski]

What Matt said! (only the second repmat to be spelled correctly)

or:

[xx yy] = meshgrid(X,Y);

surf(xx,yy,Z);

[Matt Fig]

Oops, thanks for the catch, Sean de. I didn't go with MESHGRID because the dimensions don't match up. Look at the dims for X,Y,Z.

% Z is 3-by-5.

X = round(rand(3,1)*4);

Y = round(rand(1,5)*200);

[xx,yy] = meshgrid(X,Y)% Not 3-by-5...

[VISWANATH]

I tried it as well. Getting error

??? Error using ==> surf at 78

Data dimensions must agree.

[Matt Fig]

What did you try, there have been two suggestions made in the comments?

Try the repmat solution shown above, making the spelling corrections of course:

surf(repmat(X,1,77),repmat(Y,381,1),Z)

[VISWANATH]

Matt Fig, Both suggestions are leading to the same error!! i executed yours as well as Sean de's one. Still no solution....

[Sean de Wolski]

perhaps:

surf(repmat(X(:),1,77),repmat((Y(:).'),381,1),Z)

[Sean de Wolski]

Good catch with the meshgrid as well.

[VISWANATH]

Still same error.... guys if any has idea do let me know plz..

[Sean de Wolski]

The problem Viswanath is that you're not telling us everything. The above code works on my system:

X = (1:381).';

Y = (1:77);

Z = rand(381,77);

surf(repmat(X(:),1,77),repmat((Y(:).'),381,1),Z)

size(X)

size(Y)

size(Z)

ans =

381 1

ans =

1 77

ans =

381 77

So what is the FULL TEXT of the error message and what are the ACTUAL sizes.

[Sean de Wolski]

(works for plot3 and mesh as well)

[Matt Fig]

VISWANATH, you have not told us the correct dimensions if you are getting that error. Look at an example using the dimensions you give, just copy and paste:

Xe = round(rand(381,1)*4); % Your X dimensions.

Ye = round(rand(1,77)*300); % Your Y dimensions.

Ze = rand(381,77); % Your Z dimensions.

surf(repmat(Xe,1,77),repmat(Ye,381,1),Ze) % As above.

[VISWANATH]

Hi Sean, the txt file that i gave in a hyperlink is obtained from a spectrometer.

I can not assume a matrix with random numbers for Z with 381 by 77. If you could able to read all the data given in the file and able to plot then let me know. Mean while i will give a few trails with suggestions provided by you guys.

You can email me in detail if you think it is appropriate, [e-mail]

[VISWANATH]

When i import ecoli.txt file, its size is 382 by 78. I have to read first row as Y vaue and first column as X value.

At this instant size(X)= 382 by 1, size(Y)= 1by 78.

Later i modify X and Y to 381 by and 1 by 77 respectively by removing first element in X as well as Y because first element is zero.

X and Y are wavelength values in the experiment.

Now i would like delete first column and first row in ecoli so that i get matrix of size 381 by 77, which contains only intensity values.

So i modified original ecoli 382 by 78 file to 381 by 77.

Now i assume Z=ecoli; matrix of size 381 by 77.

I want now to plot surf(X,Y,Z).

I have explained clearly now....if not let me know.

[Teja Muppirala]

if isequal({size(X) size(Y) size(Z)},{[381 1] [1 77] [381 77]})

[Xgrid,Ygrid] = meshgrid(X,Y);

surf(X,Y,Z') %<-- Transpose because your data has X vertical, Y horizontal

else

disp('Your sizes are not correct.')

end

[Teja Muppirala]

Oops, I guess I didn't really need to put that meshgrid line in there

[VISWANATH]

Hey Teja, thanks for your help. I just used Z' instead of Z in surf(X,Y,Z'). I got the surface plot. Sorry for messing up myself....Thanks a mil...