[R] question about user written function (newb question)

R. Michael Weylandt michael.weylandt at gmail.com
Sun Feb 26 16:50:47 CET 2012

Short answer to a very good question: one has to use "function(x)
tail(x, 1)"  syntax to avoid using the default tail(x, 6). There are
some other ways to achieve the same thing, but I think this syntax is
generally preferred for its clarity.

Other question: yes I believe so.


On Sun, Feb 26, 2012 at 9:06 AM, knavero <knavero at gmail.com> wrote:
> Quick newb question about R relating to the line of code below:
> rawCool = read.zoo("cooling.txt", FUN = as.chron, format = "%m/%d/%Y %H:%M",
> sep = "\t", aggregate = function(x) tail(x, 1))
> I'm wondering what the specifics are for the argument where it has
> "aggregate = function(x) tail(x, 1)". I understand that it removes the last
> row of duplicates/aggregates in the zoo series. I'm confused as to why
> "tail(x, 1)", a built in function in the utils package, requires the coder
> to treat it as a user written function thus defining the assignment, in this
> case an argument, with "function(x)". Why can't the coder just write
> "tail(x, 1)" instead? Also, with the argument 'x', within tail, I'm assuming
> it's looking at all columns simultaneously within the zoo series? Is that
> correct to say? Thanks.
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