Hi Rui, Marc, and Gabor,
Thanks for your replies to my question. All were helpful and it was interesting
to see how different people approach various aspects of the same problem.
Spent some time this weekend looking at Rui's solution, which is certainly much
clearer than my own. Managed to figure out pretty much all the details of how
it works. Also managed to tweak it slightly in order to make it do exactly what
I wanted. (See revised code below.)
Still have a couple of questions though. The first concerns the insertion of
the code "Y > 2012" to set year values beyond 2012 to NA (on line 10 of the
function below). When I add this (or use it in place of "nchar(Y) > 4"), the
code succesfully finds the problem date "05/16/2015". After that though, it
produces the following error message:
Error in if (any(is.na(x) & M != "un" & Y != "un")) cat("Warning: Invalid date
values in", : missing value where TRUE/FALSE needed
Why is this happening? If the code correctly correctly handles the date
"06/20/1840" without producing an error, why can't it do likelwise with
"05/16/2015"?
The second question is why it's necessary to put "x" on line 15 following
"cat("Warning ...)". I know that I don't get any date columns if I don't
include this but am not sure why.
The third question is whether it's possible to change the class of the date
variables without using a for loop. I played around with this a little but
didn't find a vectorized alternative. It may be that this is not really
important. It's just that I've read in several places that for loops should be
avoided wherever possible.
Thanks,
Paul
##########################################
#### Code for detecting invalid dates ####
##########################################
#### Test Data ####
connection <- textConnection("
1 11/23/21931 05/23/2009 un/17/2011
2 06/20/1840 02/30/2010 03/17/2011
3 06/17/1935 12/20/2008 07/un/2011
4 05/31/1937 01/18/2007 04/30/2011
5 06/31/1933 05/16/2015 11/20/un
")
TestDates <- data.frame(scan(connection,
list(Patient=0, birthDT="", diagnosisDT="", metastaticDT="")))
close(connection)
#### Input Data ####
TDSaved <- TestDates
#### List of Date Variables ####
DateNames <- c("birthDT", "diagnosisDT", "metastaticDT")
#### Date Function ####
fun <- function(Dat){
f <- function(jj, DF){
x <- as.character(DF[, jj])
x <- unlist(strsplit(x, "/"))
n <- length(x)
M <- x[seq(1, n, 3)]
D <- x[seq(2, n, 3)]
Y <- x[seq(3, n, 3)]
D[D == "un"] <- "15"
Y <- ifelse(nchar(Y) > 4 | Y > 2012 | Y < 1900, NA, Y)
x <- as.Date(paste(Y, M, D, sep="-"), format="%Y-%m-%d")
if(any(is.na(x) & M != "un" & Y != "un"))
cat("Warning: Invalid date values in", jj, "\n",
as.character(DF[is.na(x), jj]), "\n")
x
}
Dat <- data.frame(sapply(names(Dat), function(j) f(j, Dat)))
for(i in names(Dat)) class(Dat[[i]]) <- "Date"
Dat
}
#### Output Data ####
TD <- TDSaved
#### Read Dates ####
TD[, DateNames] <- fun(TD[, DateNames])
TD
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
