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Re: Dynamically resizing arrays [message #42408]

Mon, 07 February 2005 09:01

Michael Wallace
Messages: 409
Registered: December 2003

Senior Member

Rick Towler wrote:
> Adding data row by row like this can be a little inefficient as you are
> forcing IDL to allocate RAM for every iteration. I have found it to be
> a bit quicker to grow the array in chunks appropriate for your application.

[snip]

> ; grow array if needed - adding 100 rows at a time
> if (nrows eq totrows - 1) then begin
> array_init = [[array_init],[INTARR(100,100)]]
> totrows = totrows + 100
> endif

One other common solution is to multiply your current number of rows by
2 rather than adding a constant. If your array grows past the initial
mark you've set, this exponential algorithm will require fewer array
resize operations than the linear algorithm, and hence improve
efficiency. The one caveat is that if your array grows really large,
doubling the array might use up way too much memory. There are benefits
from both approaches -- it just depends on the nature of your data and
how large you think it may grow.

-Mike

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[Message index]

		Re: Dynamically resizing arrays By: Michael Wallace on Mon, 07 February 2005 09:01
		Re: Dynamically resizing arrays By: netnews.comcast.net on Sat, 05 February 2005 20:08
		Re: Dynamically resizing arrays By: Andrew[2] on Fri, 04 February 2005 20:04
		Re: Dynamically resizing arrays By: kenklare on Wed, 09 February 2005 11:00

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