First Steps with R Activity | Bosco Morales

Vectors

testing

pitches_by_innings <- c(12,15,10,20,10)
pitches_by_innings

[1] 12 15 10 20 10

strikes_by_inning <- c(9, 12, 6, 14, 9)
strikes_by_inning

[1]  9 12  6 14  9

Question_4: Define two vectors,runs_per_innings and hits_per_innings, each with five elements.

runs_per_innings <- rep(2,5)

runs_per_innings

[1] 2 2 2 2 2

hits_per_innings <- 1:5

hits_per_innings

[1] 1 2 3 4 5

Practice sequence from 2 to 13 with intervals of 3

seq (2,13, by=3)

[1]  2  5  8 11

Adding vectors

pitches_by_innings + strikes_by_inning

Comparig vectors

pitches_by_innings == strikes_by_inning

[1] FALSE FALSE FALSE FALSE FALSE

Find the length of a vector

length(pitches_by_innings)

[1] 5

Find the minimum value of a vector

min(pitches_by_innings)

[1] 10

Find the average value in a vector

mean(pitches_by_innings)

[1] 13.4

Question_5: Get the first element of hits_per_9innings.

hits_per_innings[1]

[1] 1

Question_6: Get the last element of hits_per_9innings.

hits_per_innings[length(hits_per_innings)]

[1] 5

You can also extract multiple values from a vector. For instance to get the 2nd through 4th values use.

runs_per_innings[c(2:4)]

[1] 2 2 2

Vectors can have strings or logical values

player_positions <- c("catcher", "pitcher", "infielders", "outfielders")

Data Frames

data.frame ( bonus=c(2,3,1), active_roaster=c("yes","No","Yes"), 
             salary=c(1.5,2.5,1))

Using tables

x <- c("Yes","No", "No", "Yes", "Yes")

table(x)

x
 No Yes 
  2   3 

Numerical measures of center and spread

’’’ Suppose, MLB Teams’ CEOs yearly compensations are sampled and the following are found (in millions)

12 .4 5 2 50 8 3 1 4 0.25 ’’’

ceo_salaries <- c(12, 0.4, 2, 15, 8, 3, 1, 4, 0.25)

Mean

mean (ceo_salaries)

[1] 5.072222

Variance

var(ceo_salaries)

[1] 28.95944

Standard Deviation

sd (ceo_salaries)

[1] 5.381398

Median

median (ceo_salaries)

[1] 3

Tukey’s Five Number Summary

fivenum(ceo_salaries)

[1]  0.25  1.00  3.00  8.00 15.00

Mode Function

getMode <- function (x) {
    ux <- unique (x)
    ux[which.max((tabulate(match(x, ux))))]
}

Most frequent value in pitches_by_innings

pitches_by_innings

[1] 12 15 10 20 10

getMode(pitches_by_innings)

[1] 10

strikes_by_inning

[1]  9 12  6 14  9

getMode(strikes_by_inning)

[1] 9

Question_8: Summarize the following survey with the table() command:

What is your favorite day of the week to watch baseball? A total of 10 fans submitted this survey.

game_day <- c("Saturday", "Saturday", "Sunday", "Monday", "Saturday","Tuesday", "Sunday", "Friday", "Friday", "Monday")

table(game_day)

game_day
  Friday   Monday Saturday   Sunday  Tuesday 
       2        2        3        2        1 

Question_9: What is the most frequent answer recorded in the survey? Use the getMode function to compute results.

getMode(game_day)

[1] "Saturday"