R-alpha: NA in data frame not detected
Friedrich Leisch
Friedrich.Leisch@ci.tuwien.ac.at
Fri, 27 Jun 1997 16:29:58 +0200
NA's in a data frame are not handled properly, if the data frame was
read in using read.table (but I'm not sure if that is the reason of
the problems):
(I'm using Debian Linux 1.3)
If I read the file
***************
1 2
2 3
3 4
4 5
? 6
6 7
7 8
8 9
***************
into R using read.table I run into troubles:
R : Copyright 1997, Robert Gentleman and Ross Ihaka
Version 0.49 Beta (April 23, 1997)
R is free software and comes with ABSOLUTELY NO WARRANTY.
You are welcome to redistribute it under certain conditions.
Type "license()" for details.
R> x<-read.table("xxx", na.strings=3D"?")
R> x
V1 V2
1 1 2
2 2 3
3 3 4
4 4 5
5 NA 6
6 6 7
7 7 8
8 8 9
R> complete.cases(x)
[1] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
R> x$V1
[1] 1 2 3 4 NA 6 7 8
R> x$V1[5]
[1] NA
R> is.na(x$V1[5])
[1] FALSE
but if I create the same dataframe in R I get the expected results:
R> z<-data.frame(V1=3Dc(1:4, NA, 6:8), y2=3D2:9)
R> z
V1 y2
[1,] 1 2
[2,] 2 3
[3,] 3 4
[4,] 4 5
[5,] NA 6
[6,] 6 7
[7,] 7 8
[8,] 8 9
R> complete.cases(z)
[1] TRUE TRUE TRUE TRUE FALSE TRUE TRUE TRUE
R> is.na(z$V1[5])
[1] TRUE
Can anybody confirm this?
--=20
-------------------------------------------------------------------
Friedrich Leisch =20
Institut f=FCr Statistik Tel: (+43 1) 58801 4541
Technische Universit=E4t Wien Fax: (+43 1) 504 14 98
Wiedner Hauptstra=DFe 8-10/1071 Friedrich.Leisch@ci.tuwien.ac.at
A-1040 Wien, Austria http://www.ci.tuwien.ac.at/~leisch
PGP public key http://www.ci.tuwien.ac.at/~leisch/pgp.key
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