[R] Is there a better way to check if an element of a list exists than using match on names?

Paul.Rustomji at csiro.au Paul.Rustomji at csiro.au
Wed Jul 30 00:20:33 CEST 2008

Hello R mailing list

Is there a better way than this to see if an element exists *within* a
list object :

#generate "file.txt" using current routine

#load file to a list called "ipf"
f <- function(.file){source(.file,local=TRUE);as.list(environment())}
ipf<- f("file.txt")


#this is the bit I need help with...
res <- match("var1",names(ipf)) # returns result > 0 if "var" exists
within ipf ie. TRUE
res <- match("var3",names(ipf)) #returns NA as "var3" is not in ipf ie.

I have tried the exists function but cannot get it to apply to items of
a list (though can get it to see if the list exists as an object...)


Paul Rustomji
Rivers and Estuaries
CSIRO Land and Water
GPO Box 1666
Canberra ACT 2601

ph +61 2 6246 5810
mobile 0406 375 739

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