Plotting how multiple things change over time: spagetti plots

Plotting multiple lines using interaction.plot()

See http://www.ats.ucla.edu/stat/r/faq/spagplot.htm for information

Make data

Week <- c(1:7,1:7)
Count <- c(32,37,35,31,19,8,28,17,15,17,14,13,22,30)
Sex <- c(rep("Buck",7),rep("Doe",7))

dat <- data.frame(Week, Count, Sex)

plot w/ interaction.plot()

interaction.plot(dat$Week, dat$Count, trace.factor = dat$Sex)

I wrote my own function before I remembered interaction.plot

plot.multiple.lines <- function(y.var, x.var, group.column, data){
  levs <- levels(data[[group.column]])
  
  n.levs <- length(levs)
  
  i.1 <- which(data[group.column] == levs[1])
  plot(data[i.1,y.var] ~ data[i.1,x.var], type = "b")
  
  for(i in 2:length(levs)){
    i.x <- which(data[group.column] == levs[i])
    points(data[i.x,y.var] ~ data[i.x,x.var], type = "b", col = i)
  }
}

# Test the function

plot.multiple.lines(y.var = "Count", x.var = "Week", group.column = "Sex", data = dat)