condition has length > 1 for LL denominator

x <- read.table(textConnection("arrive  depart  intercept

 closeAllConnections()
 denom <- lapply(split(x, x$intercept), function(.int){

denom

?Posted to another thread a response to this posting ( and to all those who wanted R on an iPad, I say "forget it"
---------

The if function only takes an argument of length 1 (as the warning says):

?"if"

Many such confusions are resolved by looking at :

?ifelse

--
David
On Nov 1, 2011, at 4:45 PM, "M. Tran" <michellev.tran at gmail.com> wrote:

I have a dataset called "results" that looks like this:

arrive ?depart ?intercept
?1 ? ? ? ?1 ? ? ? ? ?1
?1 ? ? ? ?2 ? ? ? ? ?1
?1 ? ? ? ?3 ? ? ? ? ?1
?1 ? ? ? ?2 ? ? ? ? ?2
?1 ? ? ? ?3 ? ? ? ? ?2
?1 ? ? ? ?3 ? ? ? ? ?3
?2 ? ? ? ?2 ? ? ? ? ?2
?2 ? ? ? ?3 ? ? ? ? ?2
?3 ? ? ? ?3 ? ? ? ? ?3

where arrive is the period of arrival, depart is the period of departure,
and intercept is the period in which that person was counted. ?I'm trying to
construct the denominator for a likelihood function using the following
function. ?For the first row in "results", for example, I want the
denominator to be the sum of all possible arrive/depart combinations an
interceptor in period 1 could observe: exp(P_1_1) + exp(P_1_2) + exp(P_1_3)
(i.e. P_arrive_depart).

get_denominator = function(intercept, periods_per_day)
? ?{
? ?denominator ? ?= ? ?array("(", nrow(results))
? ?for (arrival in 1:periods_per_day)
? ?{
? ? ? ?for (departure in arrival:periods_per_day)
? ? ? ?{
? ? ? ? ? ?while (arrival <= intercept & intercept <= departure)
? ? ? ? ? ?{
? ? ? ?addition_to_denom ? ?= ? ?paste("P", arrival, departure, sep = "_")
? ? ? ? ? ? ? ?if (nchar(denominator) == 1)
? ? ? ? ? ? ? ?{
? ? ? ?denominator ? ? ? ?= ? ?paste(denominator, "exp(", addition_to_denom, ")", sep =
"")
? ? ? ? ? ? ? ?}
? ? ? ? ? ? ? ?else
? ? ? ? ? ? ? ?{
? ? ? ?denominator ? ? ? ?= ? ?paste(denominator, " + exp(", addition_to_denom, ")", sep =
"")
? ? ? ? ? ? ? ?}
? ? ? ? ? ?}
? ? ? ?}
? ?}
? ? ? ?denominator ? ? ? ?= ? ?paste(denominator, ")")
? ? ? ?return(denominator)
? ?}


denominator ? ?= ? ?get_denominator(intercept ? ? ? ?= ? ?results[,"intercept"],
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?periods_per_day ? ?= ? ?3)


I'm getting the following warning message:

In if (arrival <= intercept & intercept <= departure) { ... :
?the condition has length > 1 and only the first element will be used.

As written, the code gives me the denominator for a period 1 interceptor for
every single row!

I'm having trouble figuring out how I should re-write this code. ?Any
suggestions would be greatly appreciated.



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