| Re: list manipulation [message #78799] |
Sun, 18 December 2011 10:46 |
d.poreh
Messages: 406
Registered: October 2007
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Senior Member |
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On Dec 18, 10:29 am, greg.a...@googlemail.com wrote:
> I tried like this, which works:
>
> IDL> b=list(a[0],a[1],a[2],/extract)
> IDL> print,b
> 1
> 2
> 3
> 2
> 3
> 4
> 5
>
> ..but in real life, 'a' contains hundreds of short arrays, so that line's impractical. The following, which I could easily make - and would expect to be equivalent - doesn't work:
>
> IDL> b=list(a[[0,1,2]],/extract)
> IDL> print,b
> 1 2 3
> 2
> 3 4 5
>
> Am I missing something obvious?
>
> cheers,
> Greg
Now it is something that sound working!!
Cheers,
Dave
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| Re: list manipulation [message #78800 is a reply to message #78799] |
Sun, 18 December 2011 10:29  |
greg.addr
Messages: 160
Registered: May 2007
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Senior Member |
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I tried like this, which works:
IDL> b=list(a[0],a[1],a[2],/extract)
IDL> print,b
1
2
3
2
3
4
5
..but in real life, 'a' contains hundreds of short arrays, so that line's impractical. The following, which I could easily make - and would expect to be equivalent - doesn't work:
IDL> b=list(a[[0,1,2]],/extract)
IDL> print,b
1 2 3
2
3 4 5
Am I missing something obvious?
cheers,
Greg
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| Re: list manipulation [message #78801 is a reply to message #78800] |
Sun, 18 December 2011 10:22 |
greg.addr
Messages: 160
Registered: May 2007
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Senior Member |
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Thanks for that, Vincent (and the pedagogical device wasn't wasted on me!) This extract keyword is what I need, I think - except that it doesn't work the way I hoped in my case:
IDL> a=list()
IDL> a.add,[1,2,3]
IDL> a.add,2
IDL> a.add,[3,4,5]
IDL> b=list(a,/extract)
IDL> print,b
1 2 3
2
3 4 5
I thought - ok, it thinks that's just one element, so what if I add another:
IDL> b=list(a,[1],/extract)
IDL> print,b
1 2 3
2
3 4 5
1
Still no. How would you get [1,2,3,2,3,4,5] from a?
cheers,
Greg
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| Re: list manipulation [message #78802 is a reply to message #78801] |
Sun, 18 December 2011 06:59 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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DavePoreh writes:
>
> On Dec 18, 4:33 am, Vincent Sarago <vincent.sar...@orange.fr> wrote:
>> Hello Greg,
>>
>> normally with the List object you have to use the 'FindValue' method :
>>
>> IDL> A = indgen(10)
>> IDL> B = indgen(10) + 10
>> IDL> C = indgen(3) + 50
>> IDL> lis = list(a,b,c, /extract)
>> IDL> d = l.FindValue(10)
>> IDL> print, d
>> 10
>>
>> vincent
>
> that is not working for me!!!
A common pedagogical device, used sometimes on exams,
and extensively in newsgroups such as this, is to
throw a little misdirection into the answer by
slightly mistyping one of the otherwise clear
directions. This not only gives the end user
a sense of accomplishment in figuring something out
for him or herself, but allows the answer provider
to imagine that he isn't doing ALL the damn work!
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")
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| Re: list manipulation [message #78803 is a reply to message #78802] |
Sun, 18 December 2011 04:43 |
d.poreh
Messages: 406
Registered: October 2007
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Senior Member |
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On Dec 18, 4:33 am, Vincent Sarago <vincent.sar...@orange.fr> wrote:
> Hello Greg,
>
> normally with the List object you have to use the 'FindValue' method :
>
> IDL> A = indgen(10)
> IDL> B = indgen(10) + 10
> IDL> C = indgen(3) + 50
> IDL> lis = list(a,b,c, /extract)
> IDL> d = l.FindValue(10)
> IDL> print, d
> 10
>
> vincent
that is not working for me!!!
Dave
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| Re: list manipulation [message #78804 is a reply to message #78803] |
Sun, 18 December 2011 04:33 |
Vincent Sarago
Messages: 34
Registered: September 2011
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Member |
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Hello Greg,
normally with the List object you have to use the 'FindValue' method :
IDL> A = indgen(10)
IDL> B = indgen(10) + 10
IDL> C = indgen(3) + 50
IDL> lis = list(a,b,c, /extract)
IDL> d = l.FindValue(10)
IDL> print, d
10
vincent
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