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Re: Questions about NG image with (log) axis [message #85441 is a reply to message #85440]

Tue, 06 August 2013 23:53

Fabzi
Messages: 305
Registered: July 2010

Senior Member

Hi Xin Tao,

On 08/07/2013 08:38 AM, Xin Tao wrote:
> data = dist(300)
>
> My question 1: What determines the size of the image?
> If I have
>
> x=dindgen(300)*2
> y=dindgen(300)
>
> then im=image(data, x, y, axis_style=2) will give me an elongated image.
>
> If I have
> x=dindgen(300)
> y=dindgen(300)
>
> then im=image(data, x, y, axis_style=2) will give me an square image.
>
> This behavior of the IMAGE function is strange to me.

This is documented here I think:

ASPECT_RATIO
A floating point value indicating the ratio of the Y dimension to the X
dimension in data units. If this property is set to a nonzero value, the
aspect ratio will be preserved as the graphic is stretched or shrunk.
The default value is 0 for all graphics except images, meaning that the
aspect ratio is not fixed, but is allowed to change as the graphic is
stretched or shrunk.

IDL> y=dindgen(300)
IDL> x=dindgen(300)*2
IDL> im=image(data, x, y, axis_style=2, ASPECT_RATIO=2.)

is quadratic

>
> My question 2: This looks like a bug.
>
> If I have
>
> x=dlinear(10, 100, 300) ;; create an array from 10 to 100 with 300 elements
> y=dindgen(300)
>
> and
>
> im=image(data, x, y, /xlog, axis_style=2)
>
> the image x axis has a value from 10^20, 10^40, ..., 10^100. This is certainly wrong to me.

I don't know what dlinear does so I can't say anything here.

Cheers,

Fab

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[Message index]

		Questions about NG image with (log) axis By: Xin Tao on Tue, 06 August 2013 23:38
		Re: Questions about NG image with (log) axis By: Fabzi on Tue, 06 August 2013 23:53
		Re: Questions about NG image with (log) axis By: Xin Tao on Wed, 07 August 2013 02:22
		Re: Questions about NG image with (log) axis By: Fabzi on Wed, 07 August 2013 04:59
		Re: Questions about NG image with (log) axis By: Xin Tao on Wed, 07 August 2013 05:10
		Re: Questions about NG image with (log) axis By: chris_torrence@NOSPAM on Thu, 15 August 2013 10:37
		Re: Questions about NG image with (log) axis By: David Fanning on Thu, 15 August 2013 10:52
		Re: Questions about NG image with (log) axis By: Xin Tao on Thu, 15 August 2013 20:28

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