On Sun, 2 Dec 2007, Lauri Nikkinen wrote:
#Dear R-users,
#I have a data.frame like this:
y1 <- rnorm(10) + 6.8
y2 <- rnorm(10) + (1:10*1.7 + 1)
y3 <- rnorm(10) + (1:10*6.7 + 3.7)
y <- c(y1,y2,y3)
x <- rep(1:3,10)
f <- gl(2,15, labels=paste("lev", 1:2, sep=""))
g <- seq(as.Date("2000/1/1"), by="day", length=30)
DF <- data.frame(x=x,y=y, f=f, g=g)
DF$g[DF$x == 1] <- NA
DF$x[3:6] <- NA
DF$wdays <- weekdays(DF$g)
DF
#Frequences
g <- lapply(DF, function(x) as.data.frame(table(format(x))))
g
#NA:s are now part of factor levels. How to recode NA:s into e.g. "missing"?
x y f g wdays
"integer" "numeric" "factor" "Date" "character"
and DF$f does not have any NA levels.
The place you may think you have got NAs is in format(wdays):
they are not NA nor "NA" but "NA ". I am not sure what exactly you
want (NA is not appearing in the tables: see the 'exclude' argument),
but perhaps
lapply(DF, function(x) {
if(is.character(x)) x[is.na(x)] <- "missing"
as.data.frame(table(format(x)))
})
or
lapply(DF, function(x) {
z <- table(format(x))
names(z)[grep("^NA", names(z))] <- "missing"
as.data.frame(z)
})
or
lapply(DF, function(x) {
z <- table(x, exclude=character(0))
names(z)[is.na(names(z))] <- "missing"
as.data.frame(z)
})
?
--
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)
Oxford OX1 3TG, UK Fax: +44 1865 272595