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How to read first and last line of an ascii file FAST [message #72336]

Sun, 29 August 2010 08:32

agnarhs
Messages: 4
Registered: May 2009

Junior Member

Hello group,

My data is stored in a bunch of ascii files, each 5-10MB big. Each
line represent a sample with a timestamp. I would like to analyse all
my files by reading the timestamp from the first and last line of
every file. Getting the timestamp from the last line is the issue
here. Right now I'm doing it like

readf, fid, firstline
nlines = FILE_LINES(fnames[i])
skip_lun, fid, nlines-2, /LINES
readf, fid, lastline

skip_lun is really slow when the files are big and numerous. Does
anyone have a tip of I could do this faster? Is there a way to
directly point to the end of the file minus one line?

regards,
Agnar

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