[R] read.table: colClasses when num. of columns is unknown

[ripley@stats.ox.ac.uk]

On Wed, 27 Nov 2002, Vadim Ogranovich wrote:

> Hi,
>
> I am looking for a way to read tables that have general structure of
>
> characterTag num1 num2 ...
>
> i.e. one character column followed by an unknown to the caller (but fixed
> throughout the file) number of numeric columns. I wanted to improve the
> speed of read.table by using colClasses, but that seemed to require
> knowledge of the actual number of columns in the file. For example I tried
> colClasses=c("character", rep("numeric", 100)), here 100 is an upper
> boundary on the number of columns, and hoped read.table() would just ignore
> the unused entries. But read.table failed and printed an error message
> (proving once again that R is a production-strength software).
> Is there any way around? Note that my files do have headers so the number of
> columns should be known to read.table once it parses the header.

So read it yourself with readLines and push the header back.

-- 
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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