Helpful Code#

The very basics of R code are demonstrated below:

  1. Importing data from a URL

  2. Calculating and Displaying the Standard Descriptives and the 5-Number Summary

  3. Using the cat() function to print text and code output together with some formatting options.

  4. We also include helpful commands, for example, the code that creates functions for

    • Permutations

    • Combinations

Importing Data from a URL#

Many data sets are available on the internet in CSV format. The read.csv() function is very useful:

  1. A URL is its input.

  2. From the URL, R downloads the CSV file.

  3. From the CSV, R imports the file as a data frame.

A typical example is shown below along with extracting the column Sleep as the data vector s:

pers <- read.csv('https://faculty.ung.edu/rsinn/data/personality.csv')
head(pers,3)
s <- pers$Sleep
AgeYrSexG21CorpsResGreekVarsAthHonorGPA...PerfOCDPlayExtroNarcHSAFHSSEHSAGHSSDPHS
21 2 M Y Y 1 N N N 3.23... 105 10 142 8 11 41 40 26 27 SE
20 3 F N N 2 Y N Y 3.95... 105 3 172 16 11 46 52 26 33 SE
22 3 M Y N 2 N N N 3.06... 73 1 134 15 11 48 42 44 29 AG

Standard Descriptives and cat()#

We offer the following code from the Descriptive Statistics section. This bit is quite helpful in many cases, especially during explartory data analsyis.

cat('The standard descriptives for SLEEP\n   Mean = ', round(mean(s),2),
    '\n   Standard Deviation = ', round(sd(s),2),
    '\n   Sample Size = ', length(s),
    '\n\nThe 5-number summary for SLEEEP')
summary(s)

The standard descriptives for SLEEP
   Mean =  6.24 
   Standard Deviation =  2.13 
   Sample Size =  129 

The 5-number summary for SLEEEP

   Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
   0.50    5.00    6.50    6.24    7.50   11.00

Combination and Permutations#

In probability problem-solving, we often need to evaluate combinations and permutations in R. Below is the code we use to create these functions.

combin <- function(n, k) {
    return(factorial(n) / ( factorial(k)*factorial(n-k) )) }
perm <- function(n, k) {
    return(combin(n,k) * factorial(k))}