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Re: reading past leading and training bytes [message #49204 is a reply to message #49201]

Thu, 06 July 2006 23:47

peter.albert@gmx.de is currently offline

peter.albert@gmx.de
Messages: 108
Registered: July 2005

Senior Member

Hi Jason,

my previous poster's resonse using the f77_unformatted keyword is most
likely the correct solution to your current problem, but a general
solution for skipping any number of bytes would be:

IDL> openw, lun, filename, /get_lun
IDL> skip_it = bytarr(4) ; replace 4 by the actual number of bytes
you'd like to skip
IDL> readu, lun, skip_it

after that, the file pointer is at the correct position to read the
"real" dataset. Well, that was how I read in those fortran-geenrated
files all the time. While writing this, the idea comes to my head that
it might have benn smarter to just use

IDL> openw, lun, filename, /get_lun
IDL> point_lun, lun, 4

instead. Might be worth a try ...

Cheers,

Peter

glaciologist schrieb:

> I'm using readu to read a 101 X 55 (2D) binary file
>
> The file has leading and trailing 4 byte tags ( 00 00 56 CC in
> hexadecimal).
>
> How to skip past these??!
>
> I use this code, which successfully reads in array, but first column
> gets scrambled!~
>
> readu,1,data
> byteorder,data,/xdrtof ; byteswap needed
>
> data are output by Linux Fedora 4 Portland Group FORTRAN executable
> with -byteswapio flag set on compile
>
> With thanks!
>
> Jason Box

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[Message index]

		Re: reading past leading and training bytes By: Michael Galloy on Fri, 07 July 2006 08:01
		Re: reading past leading and training bytes By: peter.albert@gmx.de on Thu, 06 July 2006 23:47
		Re: reading past leading and training bytes By: Paul Van Delst[1] on Thu, 06 July 2006 11:20

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