| Re: idl2matlab translate-o-matic [message #19061 is a reply to message #19024] |
Tue, 22 February 2000 00:00   |
Craig Markwardt
Messages: 1869
Registered: November 1996
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Senior Member |
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"J.D. Smith" <jdsmith@astro.cornell.edu> writes:
> Craig Markwardt wrote:
>> * given two arrays, A and B: concatenate all but the last two
>> elements of A, with B. Don't try [A(0:n-3),B], or you will be in a
>> world of hurt.
>>
>
> I wouldn't say a *world* or hurt. Maybe a minor planetesimal of hurt:
>
> C=n_elements(A)>2?[A[0:n_elements(A)-3],B]:B
Okay, my creative juices weren't flowing yet. Consider that a warm-up
problem.
How about this one:
* Given two 1-d arrays, A and B: insert B into any arbitrary position
I in A.
I was hoping that it would be as easy as this, a = [a(0:i-1),b,a(i:*)],
but then the special cases get start to be overwhelming (for example when i
equals 0 or n_elements(a)). My point was that indexing with an empty
range should produce an empty list.
Instead you get this,
if i EQ 0 then begin
a = [b, a]
endif else if i EQ n_elements(a)-1 then begin
a = [a, b]
endif else begin
a = [a(0:i-1),b,a(i:*)]
endelse
And if A or B are allowed to be empty or undefined at the start then
things get even *more* hurtful (perhaps even approaching a worldful).
These are all normal set-like things I'd like to do. Thankfully there
are useful convenience routines like the Astronomy Library's
STORE_ARRAY, but somehow I think these issues could be better
addressed by making the language itself complete.
Craig
--
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Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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