# Addition
2+3## [1] 5# Subtraction
5-3## [1] 2# Multiplication
2*3## [1] 6# Division
2/3## [1] 0.6666667# Exponentiation
2^3 ## [1] 8# Square root
sqrt(2)## [1] 1.414214# Logarithms
log(2)## [1] 0.6931472log10(2)# log base 10## [1] 0.30103** Question_1: Compute the log base 5 of 10 and the log of 10.**
#Question_1: Compute the log base 5 of 10 and the log of 10.
#log base 5 of 10
log(10, base = 5)## [1] 1.430677#log of 10
log(10)## [1] 2.302585** Computing some offensive metrics in baseball**
#Batting Avg=Hits/At Bats
#comppute the batting average of a player with 29 hits in 112 at bats
BA=29/112
BA## [1] 0.2589286ba_avg =round(BA,3)
ba_avg## [1] 0.259** #Question_2:What is the batting average of a player that bats 42 hits in 212 at bats?**
#Number of hits
Number_of_hits <- 42
#Number of at bats
Number_of_at_bats <- 212
Batting_average <- Number_of_hits/Number_of_at_bats
Batting_average=round(Batting_average,3)
Batting_average## [1] 0.198#On Base Percentage
#OBP=(H+BB+HBP)/(At Bats+BB+HBP+SF)
#Let us compute the OBP for a player with the following general stats
#AB=515,H=172,BB=84,HBP=5,SF=6
OBP=(172+84+5)/(515+84+5+6)
paste(OBP," is the OBP of the player")## [1] "0.427868852459016 is the OBP of the player"OBP_Adj=round(OBP,3)
paste(OBP_Adj," is the OBP_Adj of the player")## [1] "0.428 is the OBP_Adj of the player"#Question_3:Compute the OBP for a player with the following general stats: #AB=565,H=156,BB=65,HBP=3,SF=7
#AB=565,H=156,BB=65,HBP=3,SF=7
OBP=(156+65+3)/(565+65+3+156+7)
OBP_Adj=round(OBP,3)
paste(OBP_Adj," is the OBP of the player")## [1] "0.281 is the OBP of the player"Often you will want to test whether something is less than, greater than or equal to something.
3 == 8 # Is 3 equal to 8?## [1] FALSE3 != 8# Is 3 different from 8?## [1] TRUE3 <=8 # Is 3 less than or equal to 8?## [1] TRUE3>4## [1] FALSELogical operators can be used to combine multiple logical statements(and, or, not)(&&, ||, !)
#Logical Disjunction (or)
3==3 || 3==8## [1] TRUEFALSE || FALSE## [1] FALSE# Logical Conjunction (and)
TRUE & FALSE #True AND False## [1] FALSE# Negation
! FALSE # Not False## [1] TRUE# Combination of statements
2 < 3 | 1 == 5 # 2<3 is True, 1==5 is False, True OR False is True## [1] TRUE** Assigning Values to Variables**
# Combination of statements
2 < 3 | 1 == 5 # 2<3 is True, 1==5 is False, True OR False is True## [1] TRUE** Assigning Values to Variables** In R, you can assign values to variables using the assignment operator <-
Total_Bases <- 6+5
Total_Bases## [1] 11** To see the variables that are currently defined use ls (as in “list**)
ls()## [1] "BA" "ba_avg" "Batting_average"
## [4] "Number_of_at_bats" "Number_of_hits" "OBP"
## [7] "OBP_Adj" "Total_Bases"** To delete a variable, use the rm function**
rm(Total_Bases)Vectors
pitches_by_innings <- c(12,15,10,20,10)
pitches_by_innings## [1] 12 15 10 20 10strikes_by_innings <- c(9,12,6,14,9)
strikes_by_innings## [1] 9 12 6 14 9#Question_4: Define two vectors, runs_per_9innings and hits_per_9innings, each with 5 elements.
runs_per_9innings <- c(2,3,1,4,2)
hits_per_9innings <- c(5,6,3,7,5)Replicate
#replicate the number 2 five times
rep(2,5)## [1] 2 2 2 2 2#replicate the number 3 three times
rep(3,3)## [1] 3 3 3return a range of numbers
#return a range of numbers
2:7## [1] 2 3 4 5 6 7Sequences
#return a sequence of numbers from 1 to 10 by 3
seq(1,10,by=3)## [1] 1 4 7 10#return a sequence of numbers from 2 to 13 by 3
seq(2,13,by=3)## [1] 2 5 8 11# Adding Vectors
pitches_by_innings + strikes_by_innings## [1] 21 27 16 34 19#Comparing Vectors
pitches_by_innings== strikes_by_innings## [1] FALSE FALSE FALSE FALSE FALSE# get the length of a vector
length(pitches_by_innings)## [1] 5#Find the minimum value in a vector
min(pitches_by_innings)## [1] 10#Find the Mean value in a vector
mean(pitches_by_innings)## [1] 13.4#Question_5: Get the first element of hits_per_9innings.
# get the first element of a vector
pitches_by_innings[1]## [1] 12# get the firs element of hits_per_9innings vector
hits_per_9innings[1]## [1] 5# get the last element of a vector
pitches_by_innings[length(pitches_by_innings)]## [1] 10#Question_6: Get the last element of hits_per_9innings.
# get the last element of a vector of hits_per_9innings
hits_per_9innings[length(hits_per_9innings)]## [1] 5#get the second,third and fourth elements of a vector
pitches_by_innings## [1] 12 15 10 20 10pitches_by_innings[2:4] ## [1] 15 10 20# or
pitches_by_innings[c(2,3,4)]## [1] 15 10 20player_positions <-c("Catcher","Pitcher","First Base","Second Base","Third Base","Shortstop","Left Field","Center Field","Right Field","Outfielder")
player_positions## [1] "Catcher" "Pitcher" "First Base" "Second Base" "Third Base"
## [6] "Shortstop" "Left Field" "Center Field" "Right Field" "Outfielder"Data Frames
# Create a data frame with three different elements
data_frame <- data.frame(bonus=c(2,3,1),active_roster=c("Yes","No","Yes"),salary=c(1.5,2.5,1))
data_frame## bonus active_roster salary
## 1 2 Yes 1.5
## 2 3 No 2.5
## 3 1 Yes 1.0Using Tables
#Using tables
#create a list x
X <-c("Yes","No","No","Yes","Yes")
# tablulate the list x each category(count by categories)
table(X)## X
## No Yes
## 2 3Measures of Central Tendency(Numerical measures and center of spread)
#create a vector of salaries
ceo_salaries <- c(12,.4,2,15,8,3,1,4,.25)
mean(ceo_salaries)## [1] 5.072222#Get the spread/variance of the salaries
var(ceo_salaries)## [1] 28.95944#Get the standard deviation of the salaries
sd(ceo_salaries)## [1] 5.381398#Get the median of the salaries
median(ceo_salaries)## [1] 3# Get the range of the salaries
# 12,.4,2,15,8,3,1,4,.25(raw data points)
# .25,.4,1,2,3,4,8,12,15(ordered)
fivenum(ceo_salaries)## [1] 0.25 1.00 3.00 8.00 15.00# Create a function to get the mode
getmode <- function(v) {
# get the unique values
uniqv <- unique(v)
# return the unique value with the highest frequency
uniqv[which.max(tabulate(match(v, uniqv)))]
}#Get the mode of the salaries
getmode(ceo_salaries)## [1] 12IQR(ceo_salaries)## [1] 7#Question_7:
getmode(hits_per_9innings)## [1] 5#Question_8:
game_day <-c("Saturday","Saturday","Sunday","Monday","Saturday","Tuesday","Sunday","Friday","Friday","Monday")
#tabulate the game_day vector
table(game_day)## game_day
## Friday Monday Saturday Sunday Tuesday
## 2 2 3 2 1#Question_9:
#get the mode of the game_day vector
getmode(game_day)## [1] "Saturday"