Question

I am trying to plot a time series model using R. So far I have the following code, but I'm getting an error located at the very bottom. Can you please explain what I'm doing wrong, and what I should be doing instead in order to avoid the error? As far as the data is concerned, the first column displays time (hour-by-hour) across 20 days, giving 504 rows of data and the six columns thereafter display the bike demand/usage at each individual hour for six different bike stations. I am looking to answer the following two questions:

1.) Predict the next 3 hours of the bike stations' demands. Discuss the predicted results.

2.) Aggregating your hourly data into daily data, choose the same 6 stations to predict their next three day’s bike demands. Discuss the predicted results.

Here is my code so far (with the error):

> movavg <- function(x, n, type=c("s", "t", "w", "m", "e", "r")) {
+ stopifnot(is.numeric(x), is.numeric(n), is.character(type))
+ if (length(n) != 1 || ceiling(n != floor(n)) || n <= 1)
+ stop("Window length 'n' must be a single integer greater 1.")
+ nx <- length(x)
+ if (n >= nx)
+ stop("Window length 'n' must be greater then length of time series.")
+ y <- numeric(nx)
+ if (type == "s") { # simple
+ for (k in 1:(n-1)) y[k] <- mean(x[1:k])
+ for (k in n:nx) y[k] <- mean(x[(k-n+1):k])
+ } else if (type == "t") { # triangular
+ n <- ceiling((n + 1)/2)
+ s <- movavg(x, n, "s")
+ y <- movavg(s, n, "s")
+ } else if (type == "w") { # weighted
+ for (k in 1:(n-1)) y[k] <- 2 * sum((k:1)*x[k:1]) / (k*(k+1))
+ for (k in n:nx) y[k] <- 2 * sum((n:1)*x[k:(k-n+1)]) / (n*(n+1))
+ } else if (type == "m") { # modified
+ y[1] <- x[1]
+ for (k in 2:nx) y[k] <- y[k-1] + (x[k] - y[k-1])/n
+ } else if (type == "e") { # exponential
+ a <- 2/(n+1)
+ y[1] <- x[1]
+ for (k in 2:nx) y[k] <- a*x[k] + (1-a)*y[k-1]
+ } else if (type == "r") { # running
+ a <- 1/n
+ y[1] <- x[1]
+ for (k in 2:nx) y[k] <- a*x[k] + (1-a)*y[k-1]
+ } else
+ stop("The type must be one of 's', 't', 'w', 'm', 'e', or 'r'.")
+ return(y)
+ }
> library(readxl)
> BikeDemand <- read_excel("C:/Users/16092/Desktop/CitiBike_Oct2016_BikeDemand.xlsx",
+ range = "A1:G505")
> View(BikeDemand)
> plot(BikeDemand, type = "l", col = 1, ylim = c(0, 35), main = "Types of moving averages", sub = "Oct 3 2016--Oct 23 2016", xlab = "Hours", ylab = "Bike Usage/Demand")

Error in plot.default(...) :
formal argument "type" matched by multiple actual arguments

Answer 1

You are passing a data.frame to plot function which is not a correct way. You must think about

• What should be on the x axis
• What should be on the y axis

I would suggest you read the arguments of plot function in R and read some scripts/codes for time series.