RE: [R] skip lines on a connection

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From: Vadim Ogranovich (vograno@evafunds.com)
Date: Sun 02 May 2004 - 09:35:52 EST


Message-id: <C698D707214E6F4AB39AB7096C3DE5A54B32D8@phost015.intermedia.net>

Unfortunately, seek only works in terms of bytes not lines and I only
know how many lines I need to skip, but not bytes.

-----Original Message-----
From: Gabor Grothendieck [mailto:ggrothendieck@myway.com]
Sent: Saturday, May 01, 2004 3:44 PM
To: r-help@stat.math.ethz.ch
Subject: Re: [R] skip lines on a connection

?seek

Vadim Ogranovich <vograno <at> evafunds.com> writes:

:
: Hi,
:
: I am looking for an efficient way of skipping big chunks of lines on a
: connection (not necessarily at the beginning of the file). One way is
to
: use read lines, e.g. readLines(1e6), but a) this incurs the overhead
of
: construction of the return char vector and b) has a (fairly remote)
: potential to blow up the memory.
:
: Another way would be to use scan(), e.g.
:
: scan(con, skip=1e6, nmax=0)
:
: but somehow this doesn't work:
:
: > scan(con, skip=10, nmax=0)
: Error in scan(con, skip = 10, nmax = 0) :
: "scan" expected a real, got "A;12;0;"
:
: I can stick to readLines, but am curious if there is a better way.
:
: I use R-1.8.1 on RH-7.3.
:
: Thanks,
: Vadim

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