How to adjust the start of a series to zero? (i.e. subtract the first value from the sequence)
On Jul 2, 2012, at 2:21 AM, Bert Gunter wrote:
Hi Kristina: That's because I gave you the wrong function. It should be "with" not "within", as: sort2v4$adj_mean<-with(sort2v4, ave(mean, point, FUN=function(x)x- x[1])) within(dat,...) returns dat suitably modified. with (dat,...) just returns the result of the function. I frequently use within() when I mean with(), unfortunately. Sorry for the error.
That's interesting to me. I almost never use `within`. I'm wondering if I'm missing something? As I read the help page `within` is going to do something different when the expression is an assignment, so one could do the following with `within` within(dfrm, var2 <- var2/100) ... but that would have no lasting effect since its result was not assigned, so I do not se an advantage over: dfrm$var2 <- with(dfrm, var2/100) In both case one would still need to assign the result to an object, in the case of the first to 'dfrm' itself and in the second case to dfrm[['var2']]. None of the examples on the help page use `within`. Is that because it is inferior to transform?
-- Bert On Sun, Jul 1, 2012 at 6:39 PM, Kristiina Hurme <kristiina.hurme at uconn.edu>wrote:
Thanks everyone. I tried them all, and got all to work except for the last one. I tried
sort2v4$adj_mean<-within(sort2v4, ave(mean, point,
FUN=function(x)x-x[1]))
head(sort2v4)
point time mean sd adj_mean.point adj_mean.time adj_mean.mean adj_mean.sd 1 1 1 52.50100 1.5073927 1 1 52.50100 1.5073927 3 1 2 54.50182 0.8510329 1 2 54.50182 0.8510329 4 1 3 56.60174 1.5787222 1 3 56.60174 1.5787222 5 1 4 57.20000 1.2292726 1 4 57.20000 1.2292726 6 1 5 59.30000 2.2632327 1 5 59.30000 2.2632327 7 1 6 57.80089 1.4745218 1 6 57.80089 1.4745218 but am getting the columns in duplicate, rather than it performing the function. Any advice? Thanks again, Kristiina -- View this message in context: http://r.789695.n4.nabble.com/How-to-adjust-the-start-of-a-series-to-zero-i-e-subtract-the-first-value-from-the-sequence-tp4634999p4635062.html Sent from the R help mailing list archive at Nabble.com.
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