[Rd] read.table: wrong error message? (PR#10592)

[ripley at stats.ox.ac.uk]

On Sun, 20 Jan 2008, david.reitter at gmail.com wrote:

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> I believe read.table may report misleading errors. In this example,
> where a header line in a file has an incorrect number of row names (28
> instead of 29), I get the error message "duplicate row.names are not
> allowed".

The first column of your file repeats 0 and 1, and your specification 
asked for the first column to be taken as the row names: from the help 
file

      If 'row.names' is not specified and the header line has one less
      entry than the number of columns, the first column is taken to be
      the row names.

> However, I cannot not find any duplicate row names. Fixing the header
> line by adding an extra row name, however, avoids the error.

An extra *column* name?  The behaviour of header=TRUE depends on the 
number of fields on the header line: see the quote above.

> The behavior is confusing - I would expect a different error message,
> even if I should have quoted some row names.

It may have confused you, but it has been in R/S for 20 years and is 
described in the help, the 'R Data Import/Export Manual', most books on 
R/S ....

It is fortunate that you did get an error message: if you give an input 
format different from what you intended it can easily be valid but not 
that you intended.

If you want to be safer, supply the argument 'row.names'.

> I am attaching a sample file that reproduces the problem with R --
> vanilla, and then: read.table("m2").  I get it in 2.5.1 and 2.6.0.

Also 2.6,1 and R-devel, as it is the documented behaviour.

>
> PS.:
>
> R version 2.6.0 (2007-10-03)
> ...
> > x <- read.table("m2", header=T)
> Error in read.table("m2", header = T) :
>   duplicate 'row.names' are not allowed
> > traceback()
> 2: stop("duplicate 'row.names' are not allowed")
> 1: read.table("m2", header = T)
> >
>
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> Content-Disposition: attachment;
> 	filename=m2
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> 	name="m2"
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> primed rule role dist starttime target.utt rule.freq primeperiod.length dialogue.length dialogue.id words.repeated words.repeated.prop head.repeated head.freq head.pos prime.gaze target.gaze eyecontact familiar convseq length doc.score friend task.familiar same.specrule derivation pathlen distituent
> 0 vp---vbg-vp i 2 5.67 4 False 172 70 261.5322 1 0 0/7 True na None None None 1 0 1 7 135 - - 1 None - -
> 0 vp---to-vp r 1 6.03 4 False 758 13 261.5322 1 0 0/6 True na None None None 1 0 1 6 135 - - 1 None - -
> 0 vp---to-vp i 2 6.03 4 False 758 70 261.5322 1 0 0/6 True na None None None 1 0 1 6 135 - - 1 None - -
> 0 s---cc-s i 1 11.3 5 False 813 83 261.5322 1 0 2/9 True na None None None 1 0 1 9 135 - - 1 None - -
> 0 s---cc-s i 3 11.3 5 False 813 70 261.5322 1 0 0/9 True na None None None 1 0 1 9 135 - - 1 None - -
> 0 s---advp-s i 3 12.71 5 False 440 70 261.5322 1 0 0/8 True na None None None 1 0 1 8 135 - - 1 None - -
> 1 vp---ber-vp i 1 12.98 5 False 406 83 261.5322 1 0 2/7 True na None None None 1 0 1 7 135 - - 1 None - -
> 1 vp---vbg-vp i 1 13.11 5 False 172 83 261.5322 1 0 3/7 True na None None None 1 0 1 7 135 - - 1 None - -
> 1 vp---to-vp i 1 13.52 5 False 758 83 261.5322 1 0 2/6 True na None None None 1 0 1 6 135 - - 1 None - -
> 1 pp---ql-rp-pp i 1 14.12 5 False 282 83 261.5322 1 0 0/3 True na None None None 1 0 1 3 135 - - 1 None - -
> 0 pp---ql-rp-pp r 2 14.12 5 False 282 13 261.5322 1 0 0/3 True na None None None 1 0 1 3 135 - - 1 None - -
> 0 ap---ap r 2 18.75 5 False 120 13 261.5322 1 0 0/1 True na None None None 1 0 1 1 135 - - 1 None - -
> 0 pp---pp-pp i 3 22.7 6 False 429 13 261.5322 1 0 0/4 True na None None None 1 0 1 4 135 - - 1 None - -
> 1 pp---ql-rp r 2 22.7 6 False 505 83 261.5322 1 0 1/2 True na None None None 1 0 1 2 135 - - 1 None - -
> 0 pp---rp-pp r 2 23.54 6 False 1124 83 261.5322 1 0 0/2 True na None None None 1 0 1 2 135 - - 1 None - -
> 0 pp---pp-cc-rb-pp i 2 25.27 7 False 64 200 261.5322 1 0 1/6 True na None None None 1 0 1 6 135 - - 1 None - -
> 0 pp---pp-cc-rb-pp r 4 25.27 7 False 64 13 261.5322 1 0 0/6 True na None None None 1 0 1 6 135 - - 1 None - -
> 1 pp---ql-rp-pp i 2 25.99 7 False 282 200 261.5322 1 0 2/3 True na None None None 1 0 1 3 135 - - 1 None - -
> 1 pp---ql-rp-pp i 3 25.99 7 False 282 83 261.5322 1 0 0/3 True na None None None 1 0 1 3 135 - - 1 None - -
>
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-- 
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 272866 (PA)
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