| Re: populating an array [message #48163] |
Thu, 30 March 2006 12:47  |
codepod
Messages: 19
Registered: March 2006
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Junior Member |
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Subir,
Are you trying to extract every other byte of data from your array and
then convert it to an int? If so, you could take the following
approach:
data = bytarr(202000 , /nozero)
;; Note: if you're filling the array later, /nozero will save a
;; little time (skips a bzero call).
;; Read your data as you mention in your message.
;; Here, just index into your data array using the array
;; stride syntax [0:*:2] Reform creates the array shape you need.
array = reform( fix( data[ 0:*:2 ] ), 1000, 101)
;; If your IDL version doesn't support strides, you can do this
;; with indgen, but it will probably be slightly slower.
array = reform( fix( data[ lindgen(101000)*2 ] ), 1000, 101)
;; Either of these will eleminate the costly for loop
;; And if your done with data at this point, you can just free it
data = 0b
Cheers - CP
subir.vasanth@gmail.com wrote:
> Greetings!
>
> I was wondering if there was a more efficient way to populate an array
> created using the MAKE_ARRAY function. This is how I am populating the
> array right now -
>
> data = BYTARR(202000L)
> ; populate byte array with valid data from some input source
> array = MAKE_ARRAY(1000,101, Type = 2)
> offset = 0L
> FOR k = 0L, 100999L DO BEGIN
> array(k) = FIX(data, offset)
> offset = offset + 2
> ENDFOR
>
> Is there a way I can populate 'array' without using a loop to populate
> each element, and instead do a array = FIX(data)??
>
> Thanks,
> subir
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| Re: populating an array [message #48164 is a reply to message #48163] |
Thu, 30 March 2006 11:15  |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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subir.vasanth@gmail.com writes:
> I was wondering if there was a more efficient way to populate an array
> created using the MAKE_ARRAY function. This is how I am populating the
> array right now -
>
> data = BYTARR(202000L)
> ; populate byte array with valid data from some input source
> array = MAKE_ARRAY(1000,101, Type = 2)
> offset = 0L
> FOR k = 0L, 100999L DO BEGIN
> array(k) = FIX(data, offset)
> offset = offset + 2
> ENDFOR
>
> Is there a way I can populate 'array' without using a loop to populate
> each element, and instead do a array = FIX(data)??
Say what!?
What do you think this code does, exactly? It looks to me
like it creates a 1000 by 101 array filled with integer
zeros. It would be easier to do this:
array = IntArr(1000, 101)
But this seems so obvious, that I think I am missing
the intent of the question. Could you please elaborate
some more?
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
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| Re: populating an array [message #48208 is a reply to message #48164] |
Thu, 06 April 2006 13:43 |
subir.vasanth
Messages: 5
Registered: March 2006
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Junior Member |
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David,
I am trying to read in stream of bytes from a socket and then populate
an array using that data. The for loop does the job but I was trying
to get away from using the for loop and was wondering if there was a
more efficient way to populate a 2D array from a stream of bytes
(assuming you know the type of data coming in from the byte stream).
Thank you for replying!
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