Changing dates in different time zones by adding to POSIXlt
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I am running into an error when I try to localize times for "date" (a variable of class=POSIXlt) in my dataset.  Example code is as follows:

    # All dates are coded by survey software in EST(not local time)
    date <- c("2011-07-26 07:23:00", "2011-07-29 07:34:00", "2011-07-29 07:40:00")
    region <-c("USA-EST", "UK", "Singapore")

    #Change the times based on time-zone differences
    start_time<-strptime(date,"%m/%d/%Y %H:%M")
    localtime<-ifelse(region=="UK",start_time+6,start_time)
    localtime<-ifelse(region=="Singapore",start_time+12,start_time)

    #Then, I need to extract the hour and weekday
    weekday<-weekdays(localtime)
    hour<-factor(localtime)

There must be something wrong with my `"ifelse"` statement, because I get the error: `number of items to replace is not a multiple of replacement length`. Please help!