Created
November 16, 2010 15:47
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Using the ... arguments programmatically with do.call
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do.call('+', list(1, 2)) |
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f <- function(...) { | |
arguments <- list(...) # turn them into a list | |
for(arg in arguments ) { # loop through them | |
# process each argument | |
} | |
} |
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# Use the ... to make a function that can process an arbitrary number of objects | |
f1 <- function(...) { | |
arguments <- list(...) # turn them into a list | |
collection <- new.env() # store up calculations on each argument | |
counter <- # arbitrary names | |
for(arg in arguments ) { # loop through them | |
# do some processing here | |
results <- some.function.of(arg) | |
# save the result | |
assign(as.character(counter), result, envir=collection) | |
counter <- counter + 1 | |
} | |
# now here is the magic... | |
# f2 is also a function with the form `function(...) {}` | |
# ________/ | |
# / | |
do.call(f2, as.list(collection)) | |
# \________/ | |
# \ | |
# \________________________---- | |
# / | \ | |
# which is like we wrote `f2(result0, result1, result2, ...)` | |
} |
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> paste | |
function (..., sep = " ", collapse = NULL) | |
.Internal(paste(list(...), sep, collapse)) | |
<environment: namespace:base> |
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Thanks @mja!