From Andreas.Weingessel@ci.tuwien.ac.at  Wed Jan  7 10:54:25 1998
From: Andreas.Weingessel@ci.tuwien.ac.at (Andreas Weingessel)
Date: Wed, 7 Jan 1998 11:54:25 +0100
Subject: R/S difference (data frames)
Message-ID: <199801071054.LAA13594@elendil.ci.tuwien.ac.at>


In R, it is not possible to use binary operations, like -, on the
lines of a data frame, even if all columns contain numeric values. In
Splus this is possible:

R> a<-data.frame(int1=3D1:3,int2=3D4:6)
R> a[1,]-a[2,]
Error in a[1, ] - a[2, ] : non-numeric argument to binary operator

but

S>  a<-data.frame(int1=3D1:3,int2=3D4:6)
S> a[1,]-a[2,]
  int1 int2=20
1   -1   -1


If not all columns contain numeric values, both R and S give an error:

R> b<-data.frame(int1=3D1:3,int2=3D4:6,char=3Dc("a","b","c"))
R> b[1,]-b[2,]
Error in b[1, ] - b[2, ] : non-numeric argument to binary operator

S> b<-data.frame(int1=3D1:3,int2=3D4:6,char=3Dc("a","b","c"))
S> b[1,]-b[2,]
Error in Ops.factor(e1, e2): "-" not meaningful for factors
Dumped

but the following is again different:

R> b<-data.frame(int1=3D1:3,int2=3D4:6,char=3Dc("a","b","c"))
R> b[1,1:2]-b[2,1:2]
Error in b[1, 1:2] - b[2, 1:2] : non-numeric argument to binary operator

S> b<-data.frame(int1=3D1:3,int2=3D4:6,char=3Dc("a","b","c"))
> b[1,1:2]-b[2,1:2]
  int1 int2=20
1   -1   -1



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R/S difference (data frames)
Andreas Weingessel