[R] Behavior of [[ in S vs. R

[Thomas Lumley]

On Fri, 17 Oct 2003, Backlund, Jan Erik (JE) wrote:

> I am confused by the following difference in the behavior of R and S. Any
> clarification would be greatly appreciated.

sw[[2,1]] in R is short for sw[[2]][[1]], which in the case of a data
frame is sw[1,2], as your example shows.

	-thomas


> Jan Erik Backlund
> Dow AgroSciences, LLC.
> jebacklund at dow.com
>
>
> R : Copyright 2003, The R Development Core Team
> Version 1.8.0  (2003-10-08)
> > sw
>              Fertility Agriculture Examination Education Catholic
> Courtelary        80.2        17.0          15        12     9.96
> Delemont          83.1        45.1           6         9    84.84
> Franches-Mnt      92.5        39.7           5         5    93.40
> Moutier           85.8        36.5          12         7    33.77
> Neuveville        76.9        43.5          17        15     5.16
> > sw[2,1]
> [1] 83.1
> > sw[[2,1]]
> [1] 17
> >
>
> and the corresponding behaviour in S
> S-PLUS : Copyright (c) 1988, 2001 Insightful Corp.
> S : Copyright Lucent Technologies, Inc.
> Professional Edition Version 6.0.3 Release 2 for Microsoft Windows : 2001
> > sw
>              Fertility Agriculture Examination Education Catholic
>   Courtelary      80.2        17.0          15        12     9.96
>     Delemont      83.1        45.1           6         9    84.84
> Franches-Mnt      92.5        39.7           5         5    93.40
>      Moutier      85.8        36.5          12         7    33.77
>   Neuveville      76.9        43.5          17        15     5.16
> > sw[2,1]
> [1] 83.1
> > sw[[2,1]]
> [1] 83.1
>
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Thomas Lumley			Assoc. Professor, Biostatistics
tlumley at u.washington.edu	University of Washington, Seattle