I am trying to use assign and paste to assign value to existing variable
On Dec 4, 2014, at 11:24 PM, Dirkse van Schalkwyk, Theuns <theuns at sun.ac.za> wrote:
In the code below, the last line of code does what I am trying to do; however, I do not know the name of the variable before the user creates it, by choosing values in Route1. So, how can I assign values to the variables individually, when I created them using the code in lines 9-12 and assigned values in lines 15 and 16?
Lines 18 to 24 are various ways that I tried without success. Line 26 does what I want of course, but since I don't know the name of the variable beforehand I cannot use it. Maybe it will be easier to re-think the problem to use a dataframe; but I would still like to know how to do this as well.
evaluate<-function(..., envir=.GlobalEnv){ eval(parse(text=paste( ... ,sep="")), envir=envir) } #By Rufo in stackoverflow
envir <- environment()
Route1<<- c("Ao1","B1","C1","D1","Ei1")
Arrive<<- c(15,30,100,1000,5000,12000) # the time between events > exponential parameter of the arrivals
N <<- 9 # number of simulated arrivals
Route1S<<- length(Route1) # determines the number of routes in Route1
for (i in 1:(Route1S)){ # create the route variables, maybe can be vectorised, but this works for now...
assign(paste(Route1[i],"TimeB",sep = ""), rep(0, N))
assign(paste(Route1[i],"TimeE",sep = ""), rep(0, N))
assign(paste(Route1[i],"ServiceT",sep = ""), rep(0, N))
}
assign(paste(Route1[1],"TimeB",sep = ""), round(cumsum(rpois(N,Arrive[1])),2)) #time the entity comes into Source1, N values
assign(paste(Route1[1],"ServiceT",sep = ""), round(rpois(N,Arrive[2]),2)) #just service time
assign(eval(paste(Route1[1],"TimeB[",2,"]",sep = "")), 3)
x[1]<-0
assign(paste(Route1[1],"TimeB",eval("[1]"),sep = ""), 0)
sum(unlist(mget(paste("u",1:n,sep=""),envir=as.environment(-1)))))
The line above throws an error for too many closing parens, and when a paren is removed it then very reasonably complains about a missing value for "n". After a value of 3 is substituted for `n` the error becomes: Error: value for ?u1? not found. ( It's not clear what value the line provides since it is not assigned to any name.)
evaluate(paste(Route1[1],"TimeB[1]",sep = ""), envir=envir) # will find the value in Ao1TimeB[1], but how to place a new value in Ao1TimeB[1]???
I get 17.
assign(evaluate(paste(Route1[1],"TimeB[1]",sep = "")), 0) # Creates Ao1Timeb[1] as 0 but does not change the vector Ao1TimeB... assign(eval(parse(text=paste(Route1[1],"TimeB[1]",sep = ""))), 0) # does not work either and is frowned upon R-help list 106
This would be much less painful if you built one list with named descendants. You can give character values that need to be evaluated to either "[[" or "[" routlist <- list( TimeB=numeric(), TimeE=numeric() )
routlist[['TimeB']] <- lapply(paste0(Route1, "TimeB"), function(x) rep(0,N) ) routlist[['TimeE']] <- lapply(paste0(Route1, "TimeB"), function(x) rep(0,N) ) # Let's say the user input is to be placed in the 3rd location in TimeB's first entry" inp_a <- "timeB" inc_b <- 400 routlist[[inp_a]][[1]][3] <- inp_b routlist
$TimeB $TimeB[[1]] [1] 0 0 400 0 0 0 0 0 0 $TimeB[[2]] [1] 0 0 0 0 0 0 0 0 0 $TimeB[[3]] [1] 0 0 0 0 0 0 0 0 0 snipped remainder.
David. > > Ao1TimeB[1]<- 0 # this is what I am trying to do in the previous two lines > # the reason I want to do it with the paste method is because there could be 100 values in Route1 > # and expanding the method to include more such as Route2 with another 100 values etc. > # I am trying to figure out how to address these values Ao1TimeB[1], Ao1TimeB[2] etc without typing the variable name > > Theuns > The integrity and confidentiality of this email is governed by these terms / Hierdie terme bepaal die integriteit en vertroulikheid van hierdie epos. http://www.sun.ac.za/emaildisclaimer > > The integrity and confidentiality of this email is governed by these terms / Hierdie terme bepaal die integriteit en vertroulikheid van hierdie epos. http://www.sun.ac.za/emaildisclaimer > > > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. David Winsemius Alameda, CA, USA