Re: idl2matlab translate-o-matic

["J.D. Smith" <jdsmith(at)astro.cornell.edu>]

David McClain wrote:
> 
> I knew that if you thought about it you would begin to understand my
> point...
> 
> Try this one... Give me a function to return the array result of removing
> selected items from an argument array.
> 
> Since I can't pass a testing function to that routine (IDL doesn't have
> higher order functions), I will accept a routine, for illustrative purposes,
> that removes all even values from the array.
> 
> Now suppose some joker passes an array containing only even values to that
> routine...
> 
> - DM
> 

wh=where(array mod 2, cnt)
if cnt gt 0 then return,array[wh] else return, -1

I use scalars (often -1) as cheap and easy to use empty arrays.  Anything with:

 size(x,/N_DIMEN) eq 0

is patently *not* an array.  


And as far as the lack of "higher order testing functions":

function evens, arr
   return, arr mod 2 eq 0
end

function odds, arr
   return, arr mod 2
end

function exclude,arr, exc_func
   wh=where(call_function(exc_func,arr) eq 0,cnt)
   if cnt gt 0 then return,arr[wh] else return,-1
end

and to get rid of the odds, e.g.:

IDL> a=exclude(b,"odds")

JD

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