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Re: slow file-handling [message #6913]

Tue, 03 September 1996 00:00

Marty Ryba
Messages: 16
Registered: May 1996

Junior Member

In article <322ABD58.3F93@ic.ac.uk>, Jorn Helbert <jorn@ic.ac.uk> writes:
|> 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

You may be getting slowed by all the reallocation. You will also
get horrendous memory fragmentation. Do this:

t_u = fltarr(50)
b_u = dblarr(50,3)
npts = 0L
cursize = 50L
b_temp = dblarr(3)
t_temp = 0.0
WHILE NOT eof(u1) DO BEGIN
readf,u1,t_temp,foo,foo,foo,b_temp
t_u(npts) = t_temp
b_u(npts,*) = b_temp
npts = npts + 1L
IF npts EQ cursize THEN BEGIN
t_u = [temporary(t_u), fltarr(50)]
b_u = [temporary(b_u), dblarr(50,3)]
cursize = cursize + 50L
ENDIF
ENDWHILE

t_u = (temporary(t_u))(0:npts-1L)
b_u = (temporary(b_u))(0:npts-1L,*)

I generally use 50 as a block size, but you could go larger.

--
Dr. Marty Ryba | Of course nothing I say here is official
MIT Lincoln Laboratory | policy, and Laboratory affililaton is
ryba@ll.mit.edu | for identification purposes only,
| blah, blah, blah, ...

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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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