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IDL 4.0.1, best way to deal with missing/bad data [message #5783]

Fri, 09 February 1996 00:00

rfinch
Messages: 51
Registered: March 1991

Member

IDL 4.0.1, Solaris.

We are using a database (HECDSS) connected to a system of IDL routines
to view and manipulate time-series data. The database had special
values to indicate missing data, as well as the ability to store a
companion 32-bit word in which bits are set to indicate different
types of data (screened, good, reject, questionable, missing, ...).

The question comes as to the best way to handle missing/bad data
within IDL. By handle I mean don't use the data in computations, and
don't plot it. I can think of three ways:

- use the max_value keyword along with my own special, large number to
indicate bad/missing data
Problem: Not all routines use this, so it's not a universal solution.

- use the IEEE NAN to indicate the unwanted data
Problem: to avoid bogus calcs you have to use the Finite function,
an annoyance to put into every computation (we have hundreds), plus
presumably things would run slower with the Finit function.

- use the IEEE INF to indicate the unwanted data
Problem: what does plot do when it hits this? The docs hint that
calcs don't blow up on this like NAN, is that true in every case?

Any ideas which is 'best', overall?
--
"Nada burra la chamaca." A.G.
Opinions expressed are mine, not my employer or news host.
rfinch@toe.cs.berkeley.edu

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[Message index]

		IDL 4.0.1, best way to deal with missing/bad data By: rfinch on Fri, 09 February 1996 00:00
		Re: IDL 4.0.1, best way to deal with missing/bad data By: f055 on Thu, 22 February 1996 00:00
		Re: IDL 4.0.1, best way to deal with missing/bad data By: rfinch on Mon, 19 February 1996 00:00
		Re: IDL 4.0.1, best way to deal with missing/bad data By: thompson on Sat, 17 February 1996 00:00

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