degree-min-sec data
George_Heine at blm.gov writes:
Hello - Have both astronomic and geodetic data sets with values in the form "ddd:mm:ss.sssss", where dd is an integer between -180 and 180, mm is an integer between 0 and 60, and ss is a floating-point number between 0 and 60.0. In order to do anything useful with these values they need to be turned into their "decimal degree" equivalent. Assuming the data is a vector y, the following works, sort of: z<-strsplit(as.character(y),split=":") zz<-sapply(z,as.numeric) x<- t(c(1,1/60,1/3600) %*% zz) Trouble comes if there are any NA's in the data. In this case, R refuses to coerce zz into matrix form, but leaves it as a "list of lists". How can the above routine be patched up to pass NAs through? I can think of some inelegant solutions (e.g. recoding NA as "-200:-1:-1") but surely there is a better way! Or is this the wrong technique?
Not necessarily. I might try something like z <- strsplit(ifelse(is.na(y),y,"::NA")) ..etc.. There are also fancier possibilities: z <- scan(textConnection(y),sep=":",fill=TRUE,what=list(a=0,b=0,c=0)) x <- z$a + z$b/60 + z$c/3600 or even x <- with(z, a + b/60 + c/3600)
More generally, is there a way to "unzip" a character vector along some
split marker, handling irregulatirites gracefully? For example, from
y<-c("aaa#bbb", "ccc#ddd", "eee","fff"),
strsplit(y,split="#") would produce
c(c("aaa","bbb"), c("ccc","ddd"), c("eee","fff")).
Is there a way to produce instead
c(c("aaa","ccc","eee"),c("bbb","ddd","fff")) ?
?? Was that what you intended to write?
dput(strsplit(y,split="#"))
list(c("aaa", "bbb"), c("ccc", "ddd"), "eee", "fff")
O__ ---- Peter Dalgaard Blegdamsvej 3 c/ /'_ --- Dept. of Biostatistics 2200 Cph. N (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907