imagesc doesn't work

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imagesc doesn't work

Martin Seebach-2
Hello,

I'm just now looking into Octave because running Matlab remotely on my
university's servers is sucking the life out of my soul ever so slowly.

I can't really get started. I need to plot some data using imagesc
(which I assume works like the function with the same name in Matlab),
but I get an error:
octave:1> A=rand(4,3)
A =

  0.715039  0.489200  0.658305
  0.700871  0.753289  0.048180
  0.574761  0.603497  0.972616
  0.114553  0.226308  0.111039

octave:2> imagesc(A);
warning: in fopen near line 197, column 11:
warning: fopen: default open mode is now binary

and nothing happens.

octave:3> version
ans = 2.1.71

I installed the packages octave2.1, octave-forge and octave2.1-emacsen
in Ubuntu 5.10.

Any help will be greatly appreciated!

Regards,
Martin Seebach



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Re: imagesc doesn't work

Stéfan van der Walt
Try imagesc(A,100).  Maybe you missed the small window that popped up?
You need to have 'display' installed (comes with ImageMagick).

Regards
Stéfan

On Fri, Jan 13, 2006 at 02:10:58PM +0100, Martin Seebach wrote:

> Hello,
>
> I'm just now looking into Octave because running Matlab remotely on my
> university's servers is sucking the life out of my soul ever so slowly.
>
> I can't really get started. I need to plot some data using imagesc
> (which I assume works like the function with the same name in Matlab),
> but I get an error:
> octave:1> A=rand(4,3)
> A =
>
>   0.715039  0.489200  0.658305
>   0.700871  0.753289  0.048180
>   0.574761  0.603497  0.972616
>   0.114553  0.226308  0.111039
>
> octave:2> imagesc(A);
> warning: in fopen near line 197, column 11:
> warning: fopen: default open mode is now binary
>
> and nothing happens.



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Subscription information:  http://www.octave.org/archive.html
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Re: imagesc doesn't work

Martin Seebach-2
fre, 13 01 2006 kl. 18:22 +0200, skrev Stefan van der Walt:
> You need to have 'display' installed (comes with ImageMagick).

That was it, thanks! Shouldn't it be considered a bug that Octave lets
this fail silently?

OT: I got like five answers to this off-list .. doesn't people use the
mailing list?


// Martin



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Re: imagesc doesn't work

Stéfan van der Walt
On Sat, Jan 14, 2006 at 12:14:03AM +0100, Martin Seebach wrote:
> fre, 13 01 2006 kl. 18:22 +0200, skrev Stefan van der Walt:
> > You need to have 'display' installed (comes with ImageMagick).
>
> That was it, thanks! Shouldn't it be considered a bug that Octave lets
> this fail silently?
>
> OT: I got like five answers to this off-list .. doesn't people use the
> mailing list?

There are many reasons why people prefer not to use the mailing list, including

a) They think they'll look like idiots.
b) They think that they are wasting the time of the other people on the list.
c) They are not sure that their advice is technically correct.
d) Their e-mail client by default responds to the sender.

and probably a bunch of others I can't think of right now.

Personally, I know I am sometimes guilty of (a) and probably (c) --
but I think it is more important to get a conversation going, rather
than being too shy to send in your opinion/questions.  Someone may
actually benefit from your advice -- accurate or otherwise!

We are here to help each other use octave, not to ridicule each
other, so I would like to encourage people to make their replies on
the list, so that we may all learn.

Do I sound too much like a motivational speaker? :)

Cheers
Stéfan



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Re: imagesc doesn't work

Robert A. Macy
At least the flurry of responses let people know a general
population's understanding of how the programs are used and
the problems encountered. etc.

Therefore the next time programs are written, with all
those decisions that get made but aren't specified, the
impact all those little decisions will have on using the
program will be taken into account, a bit.  


...motivational speaker?

ok as long as you don't "...live in a van down by the
river."

            - Robert -

On Sat, 14 Jan 2006 23:29:10 +0200
 Stefan van der Walt <[hidden email]> wrote:

> On Sat, Jan 14, 2006 at 12:14:03AM +0100, Martin Seebach
> wrote:
> > fre, 13 01 2006 kl. 18:22 +0200, skrev Stefan van der
> Walt:
> > > You need to have 'display' installed (comes with
> ImageMagick).
> >
> > That was it, thanks! Shouldn't it be considered a bug
> that Octave lets
> > this fail silently?
> >
> > OT: I got like five answers to this off-list .. doesn't
> people use the
> > mailing list?
>
> There are many reasons why people prefer not to use the
> mailing list, including
>
> a) They think they'll look like idiots.
> b) They think that they are wasting the time of the other
> people on the list.
> c) They are not sure that their advice is technically
> correct.
> d) Their e-mail client by default responds to the sender.
>
> and probably a bunch of others I can't think of right
> now.
>
> Personally, I know I am sometimes guilty of (a) and
> probably (c) --
> but I think it is more important to get a conversation
> going, rather
> than being too shy to send in your opinion/questions.
>  Someone may
> actually benefit from your advice -- accurate or
> otherwise!
>
> We are here to help each other use octave, not to
> ridicule each
> other, so I would like to encourage people to make their
> replies on
> the list, so that we may all learn.
>
> Do I sound too much like a motivational speaker? :)
>
> Cheers
> Stéfan
>
>
>
>
-------------------------------------------------------------
> Octave is freely available under the terms of the GNU
> GPL.
>
> Octave's home on the web:  http://www.octave.org
> How to fund new projects:
>  http://www.octave.org/funding.html
> Subscription information:
>  http://www.octave.org/archive.html
>
-------------------------------------------------------------
>



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Octave's home on the web:  http://www.octave.org
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Re: imagesc doesn't work

Mike Miller-20
In reply to this post by Stéfan van der Walt
On Fri, 13 Jan 2006, Stefan van der Walt wrote:

> Try imagesc(A,100).  Maybe you missed the small window that popped up?

This happened to me and I couldn't figure out what I'd done wrong...

imagesc(rand(4))

The image is 4 pixels by 4 pixels!  All I can see is a little piece of the
window corner.  That had me stumped at first.  This is better:

imagesc(rand(4),50)

I don't have Imagemagick, so I think it's using xloadimage.

Thanks for the tip!

By the way, we find this function very useful for viewing correlation
matrices from SNPs in studies of linkage disequilibrium using haplotype
data.  Octave is quite good for this kind of thing but most people use R
(which is fine) or other software.

Mike



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