will this do it:
> x <- read.table(textConnection("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"), header = TRUE)
> closeAllConnections()
> denom <- lapply(split(x, x$intercept), function(.int){
+ paste(
+ sprintf("exp(P_%d_%d)", .int$arrive, .int$depart)
+ , collapse = "+"
+ )
+ })
>
> denom
$`1`
[1] "exp(P_1_1)+exp(P_1_2)+exp(P_1_3)"
$`2`
[1] "exp(P_1_2)+exp(P_1_3)+exp(P_2_2)+exp(P_2_3)"
$`3`
[1] "exp(P_1_3)+exp(P_3_3)"
On Tue, Nov 1, 2011 at 9:29 PM, David Winsemius <dwinsem...@comcast.net> wrote:
> 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.t...@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.
>>
>>
>>
>> --
>> View this message in context:
>> http://r.789695.n4.nabble.com/condition-has-length-1-for-LL-denominator-tp3965365p3965365.html
>> Sent from the R help mailing list archive at Nabble.com.
>>
>> ______________________________________________
>> R-help@r-project.org mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
>> and provide commented, minimal, self-contained, reproducible code.
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
--
Jim Holtman
Data Munger Guru
What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.
______________________________________________
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and provide commented, minimal, self-contained, reproducible code.
