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Re: slow file-handling [message #6917 is a reply to message #6913]

Tue, 03 September 1996 00:00

Hermann Mannstein
Messages: 22
Registered: September 1995

Junior Member

Jorn Helbert wrote:
>
> Hi,
> I have a problem reading in a large data-file
> the file consist of 57422 rows with the following format
> t foo foo foo bx by bz
>
> all double floating and I need the foo-values not. if i just read it
> line by line it takes nearly ten minutes on a sparc twenty. my read
> block is the following
> b_temp = double([0.,0.,0.])
> t_temp = [0.0]
> WHILE NOT eof(u1) DO BEGIN
> readf,u1,t_temp,foo,foo,foo,b_temp
> t_u = [t_u,t_temp]
> b_u = [b_u,b_temp]
> END
>
> I don't know before how long the file is. so I have to use the temporary
> values.
> Any ideas how to speed this up?

How about

fs=fstat(u1)
n_lines=fs.size/(7*4) ; size / bytes per line - if there are extra
; bytes you have to change this number
line={b:b_temp,foo:b_temp,t:t_temp}
all = replicate(line,n_lines_
readf,u1,all
free_lun,u1

should be faster, and you can acces your fields from the structure (a.e.
all(i).b)

--
Regards,

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Institut fuer Physik der Atmosphaere or -2558
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[Message index]

		Re: slow file-handling By: Marty Ryba on Tue, 03 September 1996 00:00
		Re: slow file-handling By: Marty Ryba on Tue, 03 September 1996 00:00
		Re: slow file-handling By: jlaw on Tue, 03 September 1996 00:00
		Re: slow file-handling By: Hermann Mannstein on Tue, 03 September 1996 00:00
		Re: slow file-handling By: James Tappin on Tue, 03 September 1996 00:00
		Re: slow file-handling By: David Theil on Mon, 02 September 1996 00:00
		Re: slow file-handling By: brian.jackel on Wed, 04 September 1996 00:00

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