gistfile1.r

fname <- 'a1.txt'
ds <- read.csv(fname,col.names = c('Date','Time','File','TimeElapsed','SongTime'),header=FALSE,stringsAsFactors=FALSE)
ds$Date <- as.Date(ds$Date)
ds$Name <- fname

timelist <- strsplit(ds$Time,split=':')

for (i in 1:length(timelist)) {
  hr <- timelist[[i]][[1]]
  mn <- timelist[[i]][[2]]
  sc <- timelist[[i]][[3]]    
  timestr <- paste(as.character(ds$Date[i])," ",hr,":",mn,":",sc,sep="")
  ds$Time[i] <- as.POSIXct(timestr)
}

labelSongs <- function(s) {
  if (s == "http://www.people.fas.harvard.edu/~mehr/1.mp3" || s == "http://www.people.fas.harvard.edu/~mehr/2.mp3")
    return("Words")
  return("Without")
}

ds$SongType <- unlist(lapply(ds$File,labelSongs))

by(ds$SongTime,ds[,c("Name","SongType","Date")],sum)
xtabs(ds$SongTime,ds[,c("Name","SongType","Date")],sum)
outds <- xtabs(SongTime ~ Name + SongType + Date, ds)