[R] skipping columns with read.fwf?

ripley@stats.ox.ac.uk ripley at stats.ox.ac.uk
Fri May 3 19:06:40 CEST 2002

On Fri, 3 May 2002, Brett A Magill wrote:

> I have a file in fwf.  It is rather large, about 40,000 rows and 40 variables (columns).  I only need about 10 variables form the data set for the analysis at hand.  Unfortunately, these 10 variables are not contiguous in the file, for example, the first is position 1-8, the next position 25-27, then 40.
> Is there a way to read the selected varaibles that I need without reading in the entire data set?

No. The first thing read.fwf does is read the whole dataset as a character
vector.  It's not designed for large files, but it may well read all the
vars in your problem if you have enough memory: the file only seems to be
of the order of 20Mb.

Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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