CSC121 - R Console
Wednesday March 7th
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> # Built-in R functions to manipulate data
> # Summing up a set of numeric data
> sum(c(1,2,3,4))
[1] 10
> prod(c(1,2,3,4))
[1] 24
> mean(c(1,2,3,4))
[1] 2.5
> sd(c(1,2,3,4))
[1] 1.290994
> var(c(1,2,3,4))
[1] 1.666667
> sqrt(var(c(1,2,3,4)))
[1] 1.290994
> # The standard deviation is the square root of the variance
> 
> # To get data from a text file on your computer, ensure your working directory is the same as where the data is located
> getwd()
[1] "/Users/csc121/Desktop"
> # setwd("PUT YOUR DIRECTORY STRING HERE")
> scan("numbers.txt")
Read 4 items
[1] 1 2 3 4
> data <- scan("numbers.txt")
Read 4 items
> data
[1] 1 2 3 4
> mean(data)
[1] 2.5
> matrix(scan("numbers.txt"), ncol=2, nrow=2)
Read 4 items
     [,1] [,2]
[1,]    1    3
[2,]    2    4
> setwd("/Users/csc121/Desktop")
> data2 <- scan("http://www.cs.utoronto.ca/~radford/csc121.S17/data2")
Read 50 items
> data2
 [1]  2.170  1.985  1.616  3.181 -0.978  1.597  0.862 -0.186  0.956  0.169 -0.403  1.107  0.965
[14]  2.155 -0.141  1.647  3.007  0.631  0.393  2.883  1.588 -0.228  1.078  0.355 -0.113  0.852
[27]  0.913  2.876 -0.499 -1.607  1.749  0.167  1.366  1.976  2.907  3.470  1.162  0.871  0.506
[40]  3.138  0.920  0.743 -1.242 -0.678  1.104  0.817  2.226  1.521  1.915  0.095
> 
> # Back to plotting 
> # One thing that is often plotted on a graph is a straight line
> # Straight lines can indicate important values
> # To draw a line we use the abline() function
> plot(data)
> abline(h=2)
> abline(v=2)
> abline(v=2, lty="dashed")
> plot(data)
> abline(v=2, lty="dashed")
> abline(h=c(2.5, 3), lty="dotted")
> # Plotting more than one graph on the same plot
> par(mfrow = c(1, 2))