| Re: how to preserve trailing Shallow dimensions! [message #61933] |
Thu, 14 August 2008 06:39  |
vino
Messages: 36
Registered: March 2008
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Member |
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Hi!
Thank you very much for the reply. As you said, my problem is with the
size function. I am doing stellar photometry. I store star position
in an array and most of the time, i am tracking more than 1 star but
the problem arose when i had only star in my image. But i think the
problem might be solved if i follow your example...
Thanks again,
Vino
On Aug 14, 2:28 pm, Vince Hradil <hrad...@yahoo.com> wrote:
> On Aug 14, 6:33 am, vino <astrocr...@gmail.com> wrote:
>
>> Hello Everyone,
>> I was wondering whether there is any way i can preserve a trailing
>> shallow dimension in array?
>
>> eg:
>> IDL> ab=make_array(2,1,1)
>> IDL> print,size(ab,/dimensions)
>> 2
>> How can i make it preserve it as 2 1 1?
>
>> Thanks and regards,
>> Vino
>
> Perhaps you should tell us why... The answer may be different than
> you expect...
>
> So, anyways, the trailing dims are "still there" as 1's:
>
> IDL> f = findgen(3,1,1)
> IDL> help, f
> F FLOAT = Array[3]
> IDL> help, f[*,0]
> <Expression> FLOAT = Array[3]
> IDL> help, f[*,0,0]
> <Expression> FLOAT = Array[3]
> IDL> print, f
> 0.000000 1.00000 2.00000
> IDL> print, f[*,*]
> 0.000000 1.00000 2.00000
> IDL> print, f[*,0]
> 0.000000 1.00000 2.00000
> IDL> print, f[*,0,0]
> 0.000000 1.00000 2.00000
> IDL> print, f[*,*,*]
> 0.000000 1.00000 2.00000
>
> If you are worried about the SIZE function:
> IDL> fsize = size(f,/dimensions)
> IDL> nx = fsize[0]
> IDL> if n_elements(fsize) gt 1 then ny = fsize[1] else ny = 1L
> IDL> if n_elements(fsize) gt 2 then nz = fsize[2] else nz = 1L
> etc...
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| Re: how to preserve trailing Shallow dimensions! [message #61934 is a reply to message #61933] |
Thu, 14 August 2008 06:28  |
Vince Hradil
Messages: 574
Registered: December 1999
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Senior Member |
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On Aug 14, 6:33 am, vino <astrocr...@gmail.com> wrote:
> Hello Everyone,
> I was wondering whether there is any way i can preserve a trailing
> shallow dimension in array?
>
> eg:
> IDL> ab=make_array(2,1,1)
> IDL> print,size(ab,/dimensions)
> 2
> How can i make it preserve it as 2 1 1?
>
> Thanks and regards,
> Vino
Perhaps you should tell us why... The answer may be different than
you expect...
So, anyways, the trailing dims are "still there" as 1's:
IDL> f = findgen(3,1,1)
IDL> help, f
F FLOAT = Array[3]
IDL> help, f[*,0]
<Expression> FLOAT = Array[3]
IDL> help, f[*,0,0]
<Expression> FLOAT = Array[3]
IDL> print, f
0.000000 1.00000 2.00000
IDL> print, f[*,*]
0.000000 1.00000 2.00000
IDL> print, f[*,0]
0.000000 1.00000 2.00000
IDL> print, f[*,0,0]
0.000000 1.00000 2.00000
IDL> print, f[*,*,*]
0.000000 1.00000 2.00000
If you are worried about the SIZE function:
IDL> fsize = size(f,/dimensions)
IDL> nx = fsize[0]
IDL> if n_elements(fsize) gt 1 then ny = fsize[1] else ny = 1L
IDL> if n_elements(fsize) gt 2 then nz = fsize[2] else nz = 1L
etc...
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| Re: how to preserve trailing Shallow dimensions! [message #61994 is a reply to message #61933] |
Sun, 17 August 2008 15:43 |
Mark[1]
Messages: 66
Registered: February 2008
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Member |
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Functions like make_array and indgen silently strip off trailing
shallow dimensions, but it is possible to override this using reform,
eg:
IDL> help, make_array(2,1,1)
<Expression> FLOAT = Array[2]
IDL> help, reform(make_array(2,1,1),2,1,1)
<Expression> FLOAT = Array[2, 1, 1]
The size function does accurately report the number of dimensions, I
think
IDL> print, size(make_array(2,1,1), /DIMENSIONS)
2
IDL> print, size(reform(make_array(2,1,1),2,1,1), /DIMENSIONS)
2 1 1
However, IDL is generally prone to chopping them off when you least
expect it, so is best to write code that will handle this.
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