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Re: Snapshot of US National Airspace Data CD-ROM
Is this what we're talking about?
http://www.faa.gov/nfdcata100/100freq.html
Does anybody have a screenshot of a plotted map from the dataset?
John C. Peterson writes:
> On Wed, Dec 15, 1999 at 08:17:02PM -0500, A. Reichert wrote:
> >
> > I may be able to help with the FTP availability. (1) What is the total
> > size,
>
> See below...
>
> >and (2) can you tell me for certain that there is no copyright
> > problems?
> >
> > - Alan
> >
>
> Will check on this...
>
> I tried compressing the "raw" NASD fixed length record data files.
> The original files are indeed pretty BIG (total > 245 MB). The good
> news is that I found out they will compress much better than I had first
> guessed. They compress to as little as roughly 3% of the original size
> (using bzip2 compression). I calculated a histogram of the "apt.txt"
> file and found that 87.3% of the characters are blanks, so these ratios
> are not too surprising in view of that. Using bzip2, all the data is
> less than 8 MB! Here's the nitty-gritty:
>
>
> gzip compression stats:
>
> no compression gzip -1 gzip -9
> ============== ======= =======
>
> aff.txt: 1492194 172587 137010
> apt.txt: 102171238 8268917 6638055
> arb.txt: 905848 52475 33527
> awy.txt: 9074325 1140017 821790
> com.txt: 1016090 91096 72156
> fix.txt: 36673780 1514892 1110183
> fss.txt: 2756449 101375 80508
> hpf.txt: 7819728 810756 645089
> ils.txt: 1929194 287609 228867
> lid.txt: 23571135 1040744 725685
> mtr.txt: 14525280 930474 707117
> nav.txt: 6753480 618244 490246
> oth.txt: 2632531 333050 226927
> pfr.txt: 11299865 421894 301844
> pja.txt: 462324 49602 40023
> ssd.txt: 1578654 212855 162090
> sua.txt: 7024368 319831 215716
> twr.txt: 13074432 705387 526279
> wxl.txt: 289419 68318 57680
> ---------- ---------- ----------
> Totals 245050334 17140123 13220792
>
> Ratios 6.99453 % 5.3951 %
>
> bzip2 compression stats:
>
> no compression bzip2 -1 bzip2 -9
> ============== ======== ========
>
> aff.txt: 1492194 131997 121245
> apt.txt: 102171238 4647535 3735390
> arb.txt: 905848 24679 23231
> awy.txt: 9074325 578409 497476
> com.txt: 1016090 46222 39982
> fix.txt: 36673780 580053 539569
> fss.txt: 2756449 54133 46939
> hpf.txt: 7819728 373526 284158
> ils.txt: 1929194 190893 172369
> lid.txt: 23571135 430320 361081
> mtr.txt: 14525280 451197 387903
> nav.txt: 6753480 359318 326460
> oth.txt: 2632531 164553 159021
> pfr.txt: 11299865 203243 165497
> pja.txt: 462324 32111 30434
> ssd.txt: 1578654 135968 118388
> sua.txt: 7024368 130183 110767
> twr.txt: 13074432 365681 310752
> wxl.txt: 289419 44735 43638
> ---------- ---------- ----------
> Totals 245050334 8944756 7474300
>
> Ratios 3.65017 % 3.05011 %
>
>
> --
> ___|___ | John C. Peterson, KD6EKQ | Try Linux for Intel x86, it's the
> -(*)- | mailto:jaypee@netcom.com | Ferarri of 32 bit operating systems!
> o/ \o | San Diego, CA U.S.A | See http://www.linux.org/ for info
> -
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