On Aug 23, 2012, at 2:02 AM, Ingmar Schuster wrote:
Thanks Rui!
Anybody with ideas regarding filling _while_ binding data frames
instead of
afterwards?
Not sure what you mean by " _while_ binding dataframes" but the
original question seems answered by this sentence from the help file
for factor:
"For a numeric x, set exclude=NULL to make NA an extra level (prints
as <NA>); by default, this is the last level."
fac <- factor(fac, exclude=NULL) # would skip all that `is.na()`,
`level=` gymnastics
If you want to loop over factor dataframe columns:
facidx <- sapply(d, is.factor)
d[ ,facidx ] <- lapply( d[ , facidx ], factor, exclude=NULL)
I see no parameters to data.frame or read.table that would allow
specifying different than the default behavior for factor().
--
David
Ingmar
2012/8/22 Rui Barradas <ruipbarra...@sapo.pt>
Hello,
Your function doesn't seem to be very difficult to generalize.
d <- read.table(text="
trg_type child_type_1
1 Scientists NA
2 of used
", header=TRUE)
str(d)
subs_na <- function(tok, na_factor_level = "NOT_REALIZED", na_num =
99999)
{
ifac <- which(sapply(tok, is.factor))
inum <- which(sapply(tok, is.numeric))
for(i in ifac) {
levels(tok[, i]) <- c(levels(tok[, i]), na_factor_level)
tok[is.na(tok[, i]), i] <- as.factor(na_factor_level)
}
for(i in inum)
tok[is.na(tok[, i]), i] <- na_num
tok
}
r1 <- substitute_na(d)
r2 <- subs_na(d)
str(r1)
str(r2)
identical(r1, r2) # TRUE
You could use the same coding for characters, Dates, etc.
Hope this helps,
Rui Barradas
Em 22-08-2012 20:16, Ingmar Schuster escreveu:
Hi,
I have a data set with variables that are _not_ missing at random.
Now I
use a package for learning a Bayesian Network which won't accept
NA as a
value. From a database I query data.frames with k,k+n,k+2n, ...
variables
(there are always at least k variables as leftmost columns). Using
rbind.fill from the reshape package on two data frames I would get
a data
frame like
trg_type child_type_1
1 Scientists NA
2 of used
Now to get rid of NA values I use the following function, which
works for
data frames with only factor values:
substitute_na <- function(tok, na_factor_level = "NOT_REALIZED") {
for (i in 1:length(tok)) {levels(tok[,i]) <- c(levels(tok[,i]),
na_factor_level)}
tok[is.na(tok)] <- as.factor(na_factor_level)
return(tok)
}
Is there a better/faster way to do it? It would also be great to
be able
to
distinguish factor columns from numeric columns and use a special
numeric
value there. The current version of rbind.fill makes no direct
reference
to
the fill value so that I could change its implementation for my
purpose.
Thanks!
Ingmar
--
Ingmar Schuster
Natural Language Processing Group
Department of Computer Science
University of Leipzig
Johannisgasse 26
04103 Leipzig, Germany
Tel. +49 341 9732205
http://asv.informatik.uni-leipzig.de/en/staff/Ingmar_Schuster
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