| Function with something like [2:*] as input [message #87137] |
Thu, 09 January 2014 12:06  |
andry
Messages: 7
Registered: March 2013
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Junior Member |
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Hi,
Could anybody help on how I can write a function so that the input will be something like the indices of an array:
For example, my function would accept a call of this format:
a= my_function([1:3]) ; to say that it will process element 1 to 3 of an array
a= my_function([[1:*]) ; to say that it will process everything from element 1 to the end. This is because most of the time, I would not know how many data I have in some array.
My problem is that I can not see how I can read that input from within the function.
I am not sure this makes sense but it will facilitate the analysis of my data.
Thanks in advance for your help,
Andry
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| Re: Function with something like [2:*] as input [message #87138 is a reply to message #87137] |
Thu, 09 January 2014 12:57  |
Matthew Argall
Messages: 286
Registered: October 2011
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Senior Member |
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Here is one way to do it. Create the function below, then
IDL> array = findgen(20)
IDL> print, SubArray(array, 1, 3)
IDL> print, SubArray(array, 1, N_Elements(array)-1)
IDL> print, SubArray(array, 1, -1)
function SubArray, array, index1, index2
return, array[index1:index2]
end
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| Re: Function with something like [2:*] as input [message #87143 is a reply to message #87138] |
Fri, 10 January 2014 04:34 |
andry
Messages: 7
Registered: March 2013
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Junior Member |
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On Thursday, January 9, 2014 5:27:31 PM UTC-3:30, Matthew Argall wrote:
> Here is one way to do it. Create the function below, then
>
>
>
> IDL> array = findgen(20)
>
> IDL> print, SubArray(array, 1, 3)
>
> IDL> print, SubArray(array, 1, N_Elements(array)-1)
>
> IDL> print, SubArray(array, 1, -1)
>
>
>
>
>
> function SubArray, array, index1, index2
>
> return, array[index1:index2]
>
> end
Thanks,
I did not know about the "-1" index.
Andry
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| Re: Function with something like [2:*] as input [message #87146 is a reply to message #87145] |
Fri, 10 January 2014 07:39 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Chris Torrence writes:
> If you really wanted to get fancy, and you have IDL 8.0 or later, you could use operator overloading. You could create an object class that is a subclass of IDL_Object, and then implement the _overloadBracketsRightSide method. Then you could do things like:
>
> myfunc = MyFunctionClass()
> a = myfunc[1:3] ; looks just like array indexing!
>
> See the examples at:
> http://www.exelisvis.com/docs/Overloading_the_Array_In.html
Right. I was going to mention that just after I explained the value of
using positional and keyword parameters. ;-)
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thue. ("Perhaps thou speakest truth.")
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