R Programming Tutorial

Posted by Derek Banas on Nov 1, 2017 in Web Design | 0 comments

In this one tutorial I will cover the basic syntax of the R programming language as well as provide numerous examples on plotting and statistical analysis. R is widely considered to be the best language for statistical analysis and data mining. R makes it extremely easy to perform numerous complex calculations with ease and its plotting system is second to none.

All of the heavily commented code follows the video below. Here is the baseball data.

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Code from the Video

# This is a comment
# Comment multiple lines in RStudio by selecting
# CMD + SHIFT + C (Mac) / CTRL + SHIFT + C Windows

# getwd() returns the working directory
# setwd("working/directory") sets the working directory

# You can highlight code and execute just it in the console

# ----- FUN STARTING EXAMPLE -----

# ----- SCATTERPLOTS -----
# Use a scatterplot to see if batting average is directly
# connected to runs produced
# Load player data
mlbPlayers = read.table(file=file.choose(),
                        header=T, sep=" ",
                        na.strings="`",
                        stringsAsFactors=F)

# Grab just RBIs and Avg for each player
# playerData is known as a data frame (Table of Data)
# We get the stats we want by passing that list in a vector
playerData = mlbPlayers[,c("RBI","AVG")]

# Create the file
png(file="player_rbi_avg.png")

# Create the plot
plot(x=playerData$RBI, y=playerData$AVG,
     xlab="RBI", ylab="AVG", main="RBIs and Average")

# Create the file
dev.off()

# ----- ASSIGNMENT -----
# You can assign a value using = or <-
myNum = 5
myNum

# ----- VARIABLES -----
# Variable names start with a letter and can contain
# numbers, underscores and dots

# Most languages use data types to define how much
# space to set asside in memory
# Variables in R are assigned R Objects

# Types are dynamic which means a variable names data
# type changes based on the data assigned to it

# Here are the Vector types
# numeric
print(class(4))

# integer
print(class(4L))

# logical (TRUE, FALSE, T, F)
print(class(TRUE))

# complex
print(class(1 + 4i))

# character
print(class("Sample"))

# raw when converted into raw bytes
print(class(charToRaw("Sample")))

# You can check an objects class with 
# is.integer(), is.numeric(), is.matrix(), is.data.frame(),
# is.logical(), is.vector(), is.character()

# You can convert to different classes with
# as.integer(), as.numeric(),...

# ----- ARITHMETIC OPERATORS -----
sprintf("4 + 5 = %d", 4 + 5)
sprintf("4 - 5 = %d", 4 - 5)
sprintf("4 * 5 = %d", 4 * 5)
sprintf("4 / 5 = %1.3f", 4 / 5)

# Modulus or remainder of division
sprintf("5 %% 4 = %d", 5 %% 4)

# Value raised to the exponent of the next
sprintf("4^2 = %d", 4^2)

# ----- VECTORS -----
# Vectors store multiple values
# Create a vector
numbers = c(3, 2, 0, 1, 8)
numbers

# Get value by index
numbers[1]

# Get the number of items
length(numbers)

# Get the last value
numbers[length(numbers)]

# Get everything but an index
numbers[-1]

# Get the 1st 2 values
numbers[c(1,2)]

# Get the 2nd and 3rd
numbers[2:3]

# Replace a value
numbers[5] = 1
numbers

# Replace the 4th and 5th with 2
numbers[c(4,5)] = 2
numbers

# sort values (decreasing can be TRUE or FALSE)
sort(numbers, decreasing=TRUE)

# Generate a sequence from 1 to 10
oneToTen = 1:10
oneToTen

# Sequence from 3 to 27 adding 3 each time
add3 = seq(from=3, to=27, by=3)
add3

# Create 10 evens from 2
evens = seq(from=2, by=2, length.out=10)
evens

# Find out if a value is in vector
sprintf("4 in evens %s", 4 %in% evens)

# rep() repeats a value/s x, a number of times and
# each defines how many times to repeat each item
rep(x=2, times=5, each=2)

rep(x=c(1,2,3), times=2, each=2)

# ----- RELATIONAL OPERATORS -----
iAmTrue = TRUE
iAmFalse = FALSE

sprintf("4 == 5 : %s", 4 == 5)
sprintf("4 != 5 : %s", 4 != 5)
sprintf("4 > 5 : %s", 4 > 5)
sprintf("4 < 5 : %s", 4 < 5)
sprintf("4 >= 5 : %s", 4 >= 5)
sprintf("4 <= 5 : %s", 4 <= 5)

# Relational operator vector tricks
oneTo20 = c(1:20)

# Create vector of Ts and Fs depending on condition
isEven = oneTo20 %% 2 == 0
isEven

# Create array of evens
justEvens = oneTo20[oneTo20 %% 2 == 0]
justEvens

# ----- LOGICAL OPERATORS -----
cat("TRUE && FALSE = ", T && F, "\n")
cat("TRUE || FALSE = ", T || F, "\n")
cat("!TRUE = ", !T, "\n")

# ----- DECISION MAKING -----
age = 18

# if, else and else if works like other languages
if(age >= 18) {
  print("Drive and Vote")
} else if (age >= 16){
  print("Drive")
} else {
  print("Wait")
}

# ----- SWITCH -----
# Used when you have a limited set of possible values
grade = "Z"

switch(grade,
       "A" = print("Great"),
       "B" = print("Good"),
       "C" = print("Ok"),
       "D" = print("Bad"),
       "F" = print("Terrible"),
       print("No Such Grade"))

# ----- STRINGS -----
str1 = "This is a string"

# String length
nchar(string1)

# You can compare strings where later letters are considered
# greater than
sprintf("Dog > Egg : %s", "Dog" > "Egg")
sprintf("Dog == Egg : %s", "Dog" == "Egg")

# Combine strings and define sperator if any
str2 = paste("Owl", "Bear", sep="")
str2

# Remove bear from the string
substr(x=str2, start=4, stop=7)

# Substitute one string with another
sub(pattern="Owl", replacement="Hawk", x=str2)

# Substitute all matches
gsub(pattern="Egg", replacement="Chicken", x="Egg Egg")

# Split string into vector
strVect = strsplit("A dog ran fast", " ")

strVect

# ----- FACTORS ------
# Factors are used when you have a limited number of values
# that are strings or integers

# Create a factor vector
direction = c("Up", "Down", "Left", "Right", "Left", "Up")
factorDir = factor(direction)

# Check if it's a Factor
is.factor(factorDir)

# A Factor object contains levels which store all possible
# values
levels(x=factorDir)

# You can define your levels and their orders
dow = c("Monday", "Tuesday", "Wednesday", "Thursday",
        "Friday", "Saturday", "Sunday")

wDays = c("Tuesday", "Thursday", "Monday")

wdFact = factor(x=wDays, levels=dow, ordered=T)

wdFact

# ----- DATA FRAMES -----
# A Data Frame is a table which contains any type 
# of data and an equal amount of data in each column

# Each row is called a record and each column a varaible

# Create customer data frame
custData = data.frame(name=c("Tom", "Sally", "Sue"),
                      age=c(43, 28, 35), 
                      stringsAsFactors=F)

custData

# Get data in row 1 column 1
custData[1,1]

# Get all data in 1st row
custData[1,1:2]

# Get all ages
custData[1:3, 2]

# Get dimensions
dim(custData)

# Add another record
recordMark = data.frame(name="Mark", age=33)
custData = rbind(custData, recordMark)
custData

# Add a column representing debt
debt = c(0, 25.50, 36, 48.19)
custData = cbind(custData, debt)
custData

# Check if money is owed
owesMoney = custData[custData$debt > 0,]
owesMoney

# ----- LOOPING -----
# Repeat until a condition is met
num = 1
repeat{
  print(num)
  num = num + 1
  if(num > 5){
    
    # Jumps out of loop
    break
  }
}

# Repeat while condition is true
while(num > 0){
  num = num - 1
  
  # next skips the rest of the loop and jumps
  # back to the top
  if(num %% 2 == 0){
    next
  }
  print(num)
}

# For can be used to cycle through a vector
# or do the same thing a specific number of times
oneTo5 = 1:5
for (i in oneTo5){
  print(i)
}

# ----- MATRICES -----
# A Matrix stores values in rows and columns

# Create a Matrix with a single column
matrix1 = matrix(data=c(1,2,3,4))
matrix1

# Create a matrix with defined rows and columns
matrix2 = matrix(data=c(1,2,3,4), nrow=2, ncol=2)
matrix2

# You can also fill by row (You can use T or TRUE)
matrix3 = matrix(data=c(1,2,3,4), nrow=2, ncol=2, byrow=T)
matrix3

# Get a Matrix dimension
dim(matrix3)

# A value at row, column
matrix3[1,2]

# Get a whole row
matrix3[1,]

# Get a whole column
matrix3[,2]

# Combine vectors to make a Matrix
matrix4 = rbind(1:3, 4:6, 7:9)
matrix4

# Get 2nd and 3rd row
matrix4[2:3,]

# Get 2nd and 3rd row by ommitting the 1st
matrix4[-1,]

# Change the first value
matrix4[1,1] = 0
matrix4

# Change the 1st row
matrix4[1,] = c(10,11,12)
matrix4

# ----- MULTI-DIMENSIONAL ARRAYS -----
# You can also create Matrices in layers

# Create a MDA with 2 rows, columns and layers
array1 = array(data=1:8, dim=c(2,2,2))
array1

# Get a value
array1[1,2,2]

# Experiment grabbing values like we did with the Matrix
# Everything is the same

# ----- FUNCTIONS -----
# A function is R is an object that performs operations
# on passed attributes and then returns results
# or simply control back

getSum = function(num1, num2){
  return(num1 + num2)
}

sprintf("5 + 6 = %d", getSum(5,6))

# If there is no return the last expression is returned
# You can define default attribute values
getDifference = function(num1=1, num2=1){
  num1 - num2
}

sprintf("5 - 6 = %d", getDifference(5,6))

# Return multiple values in a list
makeList = function(theString){
  return (strsplit(theString, " "))
}

makeList("Random Words")

# Handling missing arguments
missFunc = function(x){
  if(missing(x)){
    return("Missing Argument")
  } else {
    return(x)
  }
}

missFunc()

# Excepting variable number of arguments with ellipses
getSumMore = function(...){
  numList = list(...)
  sum = 0
  for(i in numList){
    sum = sum + i
  }
  sum
}

getSumMore(1,2,3,4)

# Disposable / Anonymous Functions are great for 
# quick operations like doubling everything in a list
numList = 1:10
dblList = (function(x) x * 2)(numList)
dblList

# Closures are functions created by functions
# Create a function that finds x to a user defined
# power
power = function(exp){
  function(x){
    x ^ exp
  }
}

cubed = power(3)
cubed(2)
cubed(1:5)

# You can store functions in lists
addFunc = list(
  add2 = function(x) x + 2,
  add3 = function(x) x + 3
)

addFunc$add2(5)

# ----- EXCEPTION HANDLING -----
# Used to gracefully handle errors
# I handle a division with string error

divide = function(num1, num2){
  tryCatch(
    num1 / num2,
    error = function(e) {
      if(is.character(num1) || is.character(num2)){
        print("Can't Divide with Strings")
      }
  })
}

divide(10,"5")

# ----- READING WRITING FILES -----
# Create a text file with headers fname lname sex
# and the data in a txt file Use `for missing values
# Save in the same directory as your R file

# Supply the file to read, whether the 1st line is 
# headers, what seperates the data, what is being used
# for missing data and false because you don't want to
# convert string vectors to factors

# myPeople is a data frame
myPeople = read.table(file=file.choose(),
                      header=T, sep=" ",
                      na.strings="`",
                      stringsAsFactors=F)
myPeople

# Add another person
donnaRecord = data.frame(fname="Donna",
                         lname="Heyward",
                         sex="female")
myPeople = rbind(myPeople, donnaRecord)

# Update a record
myPeople[7,2] = "Smith"

# Update the file by supplying the data.frame,
# the file to write, seperator, na, whether to
# quote strings, whether to include row numbers
write.table(x=myPeople, file=file.choose(),
            sep=" ", na="`",
            quote=F, row.names=F)

# Get 1st 3 records
head(myPeople, 3)

# Get remaining records
tail(myPeople)

# ----- BASIC PLOTTING -----
# R provides great plotting tools

# Plotting x y coordinates from a matrix
# 1st 5 are x and 2nd 5 are y
xy1 = matrix(data=c(1,2,3,4,5,
                    1,2,3,4,5), nrow=5, ncol=5)
plot(xy1)

# Draw a line
x2 = c(1,2,3,4,5)
y2 = c(1,2,3,4,5)
plot(x2, y2, type="l")

# Points and lines
plot(x2, y2, type="b")

# Points and lines with no space around points,
# labels, a blue line (Find more with colors())
plot(x2, y2, type="o", 
     main="My Plot", xlab="x axis", ylab="y axis",
     col="steelblue")

# pch (1-25) defines different points
# lty (1-6) defines different lines
# xlim defines the max and min x plotting region
# ylim defines the max and min y plotting region
plot(x2, y2, type="b", pch=2, lty=2,
     xlim=c(-8,8), ylim=c(-8,8))

# Multiple plots
plot(x2, y2, type="b")

# Adds straight lines at 2 and 4 coordinates
abline(h=c(2,4), col="red",lty=2)

# Draw a 2 segmented lines with starting and ending x
# and y points
segments(x0=c(2,4), y0=c(2,2), x1=c(2,4), y1=c(4,4),
         col="red",lty=2)

# Draw an arrow
arrows(x0=1.5, y0=4.55, x1=2.7, y1=3.3, col="blue")

# Print Text
text(x=1.25, y=4.75, labels="Center")

# Load a built in data.frame
plot(faithful)

# Highlight eruptions with a waiting time greater
# then 4
eruptions4 = with(faithful, faithful[eruptions > 4,])

# Draw specific points
points(eruptions4, col="red", pch=3)



# ----- MATH FUNCTIONS -----
sqrt(x=100)

# Get the power you raise the base to get x
log(x=4, base=2)

# Euler's number 2.718 to the power of x
exp(x=2)

# Sum all vector values
sum(c(1,2,3))

# Find the mean (average)
randD1 = c(1,5,6,7,10,16)
mean(randD1)

# The median (Middle Number or avg of middle 2)
median(randD1)

# Minimum value
min(randD1)

# Maximum value
max(randD1)

# Min and max
range(randD1)

# Rounding
ceiling(4.5)
floor(4.5)

# Cumulatives
cumsum(c(1,2,3))
cumprod(c(1,2,3))
cummax(c(7:9, 4:6, 1:3))
cummin(c(4:6, 1:3, 7:9))

# Generating Random samples
# Flipping a coin 10 times and weigh the probability
# of the next flip based on the previous
sample(0:1,10,replace=T)

sample(1:20,10,replace=T)

# ----- PIE CHARTS -----
# List percentages
foodPref = c(15, 35, 10, 25, 15)

# Labels associated with percentages
foodLabels = c("Spaghetti", "Pizza", "Mac n' Cheese",
           "Chicken Nuggets", "Tacos")

# Where to save the image
png(file="child_food_pref.png")

# Colors used for each option
colors = rainbow(length(foodPref))

# Create the chart
pie(foodPref, foodLabels, main="Food Prefs",
    col=colors)

# Print legend and cex shrinks the size
legend("topright", c("Spaghetti", "Pizza", "Mac n' Cheese",
                     "Chicken", "Tacos"), cex=0.8,
       fill=colors)

# Save the chart
dev.off()

# 3D Pie Chart
# Download package in console install.packages("plotrix")
# Get the library
library(plotrix)

# Name the chart file
png(file="3d_child_food_pref.png")

# Create the chart
pie3D(foodPref, labels=foodLabels, explode=0.1,
      start=pi/2, main="Food Prefs", labelcex=0.8)

# Save the chart
dev.off()

# ----- BAR CHARTS -----
# Define the bar chart file
png(file="food_pref_bar_chart.png")

# Plot the chart
barplot(foodPref, names.arg=foodLabels, xlab="Votes",
        ylab="Food Options", col=colors, 
        main="Food Prefs")

# Save File
dev.off()

# ----- REGRESSION ANALYSIS -----
# Used to study a relationship between 2 separate 
# pieces of data (What is the relation between batting
# average and RBIS)

# Create relationship model between AVG and RBIs
relation = lm(playerData$RBI~playerData$AVG)

# Create file 
png(file="RBI_AVG_Regression.png")

# Plot the chart
plot(playerData$AVG, playerData$RBI, 
     main="AVG & RBI Regression", 
     abline(lm(playerData$RBI~playerData$AVG)),
     xlab="AVG", ylab="RBIs")

# Save chart
dev.off()

# ----- MULTIPLE REGRESSION -----
# Used to study the impact on one variable from numerous 
# others
# Estimate RBIs based on other player stats
playerData2 = mlbPlayers[,c("RBI","AVG","HR","OBP",
                            "SLG","OPS")]

# Create the relationship model
relation2 = lm(playerData2$RBI ~ playerData2$AVG + 
                 playerData2$HR + playerData2$OBP +
                 playerData2$SLG + playerData2$OPS)

sprintf("Intercept : %f1.4", coef(relation2)[1])

# How stats effect RBIs
sprintf("AVG : %f1.4", coef(relation2)[2])
sprintf("HR : %f1.4", coef(relation2)[3])
sprintf("OBP : %f1.4", coef(relation2)[4])
sprintf("SLG : %f1.4", coef(relation2)[5])
sprintf("OPS : %f1.4", coef(relation2)[6])

# Calculate expected RBIs based on stats
# Evan Longoria
# RBIs   AVG   HR   OBP   SLG   OPS
# 86     .261  20  .313  .424  .737
RBIGuess = -5.05 + (372.96 * .261) + (2.56 * 20) +
  (-5.41 * .313) + (-167.37 * .424)
RBIGuess

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# This is a comment

# Comment multiple lines in RStudio by selecting

# CMD + SHIFT + C (Mac) / CTRL + SHIFT + C Windows

# getwd() returns the working directory

# setwd("working/directory") sets the working directory

# You can highlight code and execute just it in the console

# ----- FUN STARTING EXAMPLE -----

# ----- SCATTERPLOTS -----

# Use a scatterplot to see if batting average is directly

# connected to runs produced

# Load player data

mlbPlayers = read.table(file=file.choose(),

header=T, sep=" ",

na.strings="`",

stringsAsFactors=F)

# Grab just RBIs and Avg for each player

# playerData is known as a data frame (Table of Data)

# We get the stats we want by passing that list in a vector

playerData = mlbPlayers[,c("RBI","AVG")]

# Create the file

png(file="player_rbi_avg.png")

# Create the plot

plot(x=playerData$RBI, y=playerData$AVG,

xlab="RBI", ylab="AVG", main="RBIs and Average")

# Create the file

dev.off()

# ----- ASSIGNMENT -----

# You can assign a value using = or <-

myNum = 5

myNum

# ----- VARIABLES -----

# Variable names start with a letter and can contain

# numbers, underscores and dots

# Most languages use data types to define how much

# space to set asside in memory

# Variables in R are assigned R Objects

# Types are dynamic which means a variable names data

# type changes based on the data assigned to it

# Here are the Vector types

# numeric

print(class(4))

# integer

print(class(4L))

# logical (TRUE, FALSE, T, F)

print(class(TRUE))

# complex

print(class(1 + 4i))

# character

print(class("Sample"))

# raw when converted into raw bytes

print(class(charToRaw("Sample")))

# You can check an objects class with

# is.integer(), is.numeric(), is.matrix(), is.data.frame(),

# is.logical(), is.vector(), is.character()

# You can convert to different classes with

# as.integer(), as.numeric(),...

# ----- ARITHMETIC OPERATORS -----

sprintf("4 + 5 = %d", 4 + 5)

sprintf("4 - 5 = %d", 4 - 5)

sprintf("4 * 5 = %d", 4 * 5)

sprintf("4 / 5 = %1.3f", 4 / 5)

# Modulus or remainder of division

sprintf("5 %% 4 = %d", 5 %% 4)

# Value raised to the exponent of the next

sprintf("4^2 = %d", 4^2)

# ----- VECTORS -----

# Vectors store multiple values

# Create a vector

numbers = c(3, 2, 0, 1, 8)

numbers

# Get value by index

numbers[1]

# Get the number of items

length(numbers)

# Get the last value

numbers[length(numbers)]

# Get everything but an index

numbers[-1]

# Get the 1st 2 values

numbers[c(1,2)]

# Get the 2nd and 3rd

numbers[2:3]

# Replace a value

numbers[5] = 1

numbers

# Replace the 4th and 5th with 2

numbers[c(4,5)] = 2

numbers

# sort values (decreasing can be TRUE or FALSE)

sort(numbers, decreasing=TRUE)

# Generate a sequence from 1 to 10

oneToTen = 1:10

oneToTen

# Sequence from 3 to 27 adding 3 each time

add3 = seq(from=3, to=27, by=3)

add3

# Create 10 evens from 2

evens = seq(from=2, by=2, length.out=10)

evens

# Find out if a value is in vector

sprintf("4 in evens %s", 4 %in% evens)

# rep() repeats a value/s x, a number of times and

# each defines how many times to repeat each item

rep(x=2, times=5, each=2)

rep(x=c(1,2,3), times=2, each=2)

# ----- RELATIONAL OPERATORS -----

iAmTrue = TRUE

iAmFalse = FALSE

sprintf("4 == 5 : %s", 4 == 5)

sprintf("4 != 5 : %s", 4 != 5)

sprintf("4 > 5 : %s", 4 > 5)

sprintf("4 < 5 : %s", 4 < 5)

sprintf("4 >= 5 : %s", 4 >= 5)

sprintf("4 <= 5 : %s", 4 <= 5)

# Relational operator vector tricks

oneTo20 = c(1:20)

# Create vector of Ts and Fs depending on condition

isEven = oneTo20 %% 2 == 0

isEven

# Create array of evens

justEvens = oneTo20[oneTo20 %% 2 == 0]

justEvens

# ----- LOGICAL OPERATORS -----

cat("TRUE && FALSE = ", T && F, "\n")

cat("TRUE || FALSE = ", T || F, "\n")

cat("!TRUE = ", !T, "\n")

# ----- DECISION MAKING -----

age = 18

# if, else and else if works like other languages

if(age >= 18) {

print("Drive and Vote")

} else if (age >= 16){

print("Drive")

} else {

print("Wait")

}

# ----- SWITCH -----

# Used when you have a limited set of possible values

grade = "Z"

switch(grade,

"A" = print("Great"),

"B" = print("Good"),

"C" = print("Ok"),

"D" = print("Bad"),

"F" = print("Terrible"),

print("No Such Grade"))

# ----- STRINGS -----

str1 = "This is a string"

# String length

nchar(string1)

# You can compare strings where later letters are considered

# greater than

sprintf("Dog > Egg : %s", "Dog" > "Egg")

sprintf("Dog == Egg : %s", "Dog" == "Egg")

# Combine strings and define sperator if any

str2 = paste("Owl", "Bear", sep="")

str2

# Remove bear from the string

substr(x=str2, start=4, stop=7)

# Substitute one string with another

sub(pattern="Owl", replacement="Hawk", x=str2)

# Substitute all matches

gsub(pattern="Egg", replacement="Chicken", x="Egg Egg")

# Split string into vector

strVect = strsplit("A dog ran fast", " ")

strVect

# ----- FACTORS ------

# Factors are used when you have a limited number of values

# that are strings or integers

# Create a factor vector

direction = c("Up", "Down", "Left", "Right", "Left", "Up")

factorDir = factor(direction)

# Check if it's a Factor

is.factor(factorDir)

# A Factor object contains levels which store all possible

# values

levels(x=factorDir)

# You can define your levels and their orders

dow = c("Monday", "Tuesday", "Wednesday", "Thursday",

"Friday", "Saturday", "Sunday")

wDays = c("Tuesday", "Thursday", "Monday")

wdFact = factor(x=wDays, levels=dow, ordered=T)

wdFact

# ----- DATA FRAMES -----

# A Data Frame is a table which contains any type

# of data and an equal amount of data in each column

# Each row is called a record and each column a varaible

# Create customer data frame

custData = data.frame(name=c("Tom", "Sally", "Sue"),

age=c(43, 28, 35),

stringsAsFactors=F)

custData

# Get data in row 1 column 1

custData[1,1]

# Get all data in 1st row

custData[1,1:2]

# Get all ages

custData[1:3, 2]

# Get dimensions

dim(custData)

# Add another record

recordMark = data.frame(name="Mark", age=33)

custData = rbind(custData, recordMark)

custData

# Add a column representing debt

debt = c(0, 25.50, 36, 48.19)

custData = cbind(custData, debt)

custData

# Check if money is owed

owesMoney = custData[custData$debt > 0,]

owesMoney

# ----- LOOPING -----

# Repeat until a condition is met

num = 1

repeat{

print(num)

num = num + 1

if(num > 5){

# Jumps out of loop

break

}

# Repeat while condition is true

while(num > 0){

num = num - 1

# next skips the rest of the loop and jumps

# back to the top

if(num %% 2 == 0){

}

print(num)

}

# For can be used to cycle through a vector

# or do the same thing a specific number of times

oneTo5 = 1:5

for (i in oneTo5){

print(i)

}

# ----- MATRICES -----

# A Matrix stores values in rows and columns

# Create a Matrix with a single column

matrix1 = matrix(data=c(1,2,3,4))

matrix1

# Create a matrix with defined rows and columns

matrix2 = matrix(data=c(1,2,3,4), nrow=2, ncol=2)

matrix2

# You can also fill by row (You can use T or TRUE)

matrix3 = matrix(data=c(1,2,3,4), nrow=2, ncol=2, byrow=T)

matrix3

# Get a Matrix dimension

dim(matrix3)

# A value at row, column

matrix3[1,2]

# Get a whole row

matrix3[1,]

# Get a whole column

matrix3[,2]

# Combine vectors to make a Matrix

matrix4 = rbind(1:3, 4:6, 7:9)

matrix4

# Get 2nd and 3rd row

matrix4[2:3,]

# Get 2nd and 3rd row by ommitting the 1st

matrix4[-1,]

# Change the first value

matrix4[1,1] = 0

matrix4

# Change the 1st row

matrix4[1,] = c(10,11,12)

matrix4

# ----- MULTI-DIMENSIONAL ARRAYS -----

# You can also create Matrices in layers

# Create a MDA with 2 rows, columns and layers

array1 = array(data=1:8, dim=c(2,2,2))

array1

# Get a value

array1[1,2,2]

# Experiment grabbing values like we did with the Matrix

# Everything is the same

# ----- FUNCTIONS -----

# A function is R is an object that performs operations

# on passed attributes and then returns results

# or simply control back

getSum = function(num1, num2){

return(num1 + num2)

}

sprintf("5 + 6 = %d", getSum(5,6))

# If there is no return the last expression is returned

# You can define default attribute values

getDifference = function(num1=1, num2=1){

num1 - num2

}

sprintf("5 - 6 = %d", getDifference(5,6))

# Return multiple values in a list

makeList = function(theString){

return (strsplit(theString, " "))

}

makeList("Random Words")

# Handling missing arguments

missFunc = function(x){

if(missing(x)){

return("Missing Argument")

} else {

return(x)

}

missFunc()

# Excepting variable number of arguments with ellipses

getSumMore = function(...){

numList = list(...)

sum = 0

for(i in numList){

sum = sum + i

}

sum

}

getSumMore(1,2,3,4)

# Disposable / Anonymous Functions are great for

# quick operations like doubling everything in a list

numList = 1:10

dblList = (function(x) x * 2)(numList)

dblList

# Closures are functions created by functions

# Create a function that finds x to a user defined

# power

power = function(exp){

function(x){

x ^ exp

}

cubed = power(3)

cubed(2)

cubed(1:5)

# You can store functions in lists

addFunc = list(

add2 = function(x) x + 2,

add3 = function(x) x + 3

)

addFunc$add2(5)

# ----- EXCEPTION HANDLING -----

# Used to gracefully handle errors

# I handle a division with string error

divide = function(num1, num2){

tryCatch(

num1 / num2,

error = function(e) {

if(is.character(num1) || is.character(num2)){

print("Can't Divide with Strings")

}

})

}

divide(10,"5")

# ----- READING WRITING FILES -----

# Create a text file with headers fname lname sex

# and the data in a txt file Use `for missing values

# Save in the same directory as your R file

# Supply the file to read, whether the 1st line is

# headers, what seperates the data, what is being used

# for missing data and false because you don't want to

# convert string vectors to factors

# myPeople is a data frame

myPeople = read.table(file=file.choose(),

header=T, sep=" ",

na.strings="`",

stringsAsFactors=F)

myPeople

# Add another person

donnaRecord = data.frame(fname="Donna",

lname="Heyward",

sex="female")

myPeople = rbind(myPeople, donnaRecord)

# Update a record

myPeople[7,2] = "Smith"

# Update the file by supplying the data.frame,

# the file to write, seperator, na, whether to

# quote strings, whether to include row numbers

write.table(x=myPeople, file=file.choose(),

sep=" ", na="`",

quote=F, row.names=F)

# Get 1st 3 records

head(myPeople, 3)

# Get remaining records

tail(myPeople)

# ----- BASIC PLOTTING -----

# R provides great plotting tools

# Plotting x y coordinates from a matrix

# 1st 5 are x and 2nd 5 are y

xy1 = matrix(data=c(1,2,3,4,5,

1,2,3,4,5), nrow=5, ncol=5)

plot(xy1)

# Draw a line

x2 = c(1,2,3,4,5)

y2 = c(1,2,3,4,5)

plot(x2, y2, type="l")

# Points and lines

plot(x2, y2, type="b")

# Points and lines with no space around points,

# labels, a blue line (Find more with colors())

plot(x2, y2, type="o",

main="My Plot", xlab="x axis", ylab="y axis",

col="steelblue")

# pch (1-25) defines different points

# lty (1-6) defines different lines

# xlim defines the max and min x plotting region

# ylim defines the max and min y plotting region

plot(x2, y2, type="b", pch=2, lty=2,

xlim=c(-8,8), ylim=c(-8,8))

# Multiple plots

plot(x2, y2, type="b")

# Adds straight lines at 2 and 4 coordinates

abline(h=c(2,4), col="red",lty=2)

# Draw a 2 segmented lines with starting and ending x

# and y points

segments(x0=c(2,4), y0=c(2,2), x1=c(2,4), y1=c(4,4),

col="red",lty=2)

# Draw an arrow

arrows(x0=1.5, y0=4.55, x1=2.7, y1=3.3, col="blue")

# Print Text

text(x=1.25, y=4.75, labels="Center")

# Load a built in data.frame

plot(faithful)

# Highlight eruptions with a waiting time greater

# then 4

eruptions4 = with(faithful, faithful[eruptions > 4,])

# Draw specific points

points(eruptions4, col="red", pch=3)

# ----- MATH FUNCTIONS -----

sqrt(x=100)

# Get the power you raise the base to get x

log(x=4, base=2)

# Euler's number 2.718 to the power of x

exp(x=2)

# Sum all vector values

sum(c(1,2,3))

# Find the mean (average)

randD1 = c(1,5,6,7,10,16)

mean(randD1)

# The median (Middle Number or avg of middle 2)

median(randD1)

# Minimum value

min(randD1)

# Maximum value

max(randD1)

# Min and max

range(randD1)

# Rounding

ceiling(4.5)

floor(4.5)

# Cumulatives

cumsum(c(1,2,3))

cumprod(c(1,2,3))

cummax(c(7:9, 4:6, 1:3))

cummin(c(4:6, 1:3, 7:9))

# Generating Random samples

# Flipping a coin 10 times and weigh the probability

# of the next flip based on the previous

sample(0:1,10,replace=T)

sample(1:20,10,replace=T)

# ----- PIE CHARTS -----

# List percentages

foodPref = c(15, 35, 10, 25, 15)

# Labels associated with percentages

foodLabels = c("Spaghetti", "Pizza", "Mac n' Cheese",

"Chicken Nuggets", "Tacos")

# Where to save the image

png(file="child_food_pref.png")

# Colors used for each option

colors = rainbow(length(foodPref))

# Create the chart

pie(foodPref, foodLabels, main="Food Prefs",

col=colors)

# Print legend and cex shrinks the size

legend("topright", c("Spaghetti", "Pizza", "Mac n' Cheese",

"Chicken", "Tacos"), cex=0.8,

fill=colors)

# Save the chart

dev.off()

# 3D Pie Chart

# Download package in console install.packages("plotrix")

# Get the library

library(plotrix)

# Name the chart file

png(file="3d_child_food_pref.png")

# Create the chart

pie3D(foodPref, labels=foodLabels, explode=0.1,

start=pi/2, main="Food Prefs", labelcex=0.8)

# Save the chart

dev.off()

# ----- BAR CHARTS -----

# Define the bar chart file

png(file="food_pref_bar_chart.png")

# Plot the chart

barplot(foodPref, names.arg=foodLabels, xlab="Votes",

ylab="Food Options", col=colors,

main="Food Prefs")

# Save File

dev.off()

# ----- REGRESSION ANALYSIS -----

# Used to study a relationship between 2 separate

# pieces of data (What is the relation between batting

# average and RBIS)

# Create relationship model between AVG and RBIs

relation = lm(playerData$RBI~playerData$AVG)

# Create file

png(file="RBI_AVG_Regression.png")

# Plot the chart

plot(playerData$AVG, playerData$RBI,

main="AVG & RBI Regression",

abline(lm(playerData$RBI~playerData$AVG)),

xlab="AVG", ylab="RBIs")

# Save chart

dev.off()

# ----- MULTIPLE REGRESSION -----

# Used to study the impact on one variable from numerous

# others

# Estimate RBIs based on other player stats

playerData2 = mlbPlayers[,c("RBI","AVG","HR","OBP",

"SLG","OPS")]

# Create the relationship model

relation2 = lm(playerData2$RBI ~ playerData2$AVG +

playerData2$HR + playerData2$OBP +

playerData2$SLG + playerData2$OPS)

sprintf("Intercept : %f1.4", coef(relation2)[1])

# How stats effect RBIs

sprintf("AVG : %f1.4", coef(relation2)[2])

sprintf("HR : %f1.4", coef(relation2)[3])

sprintf("OBP : %f1.4", coef(relation2)[4])

sprintf("SLG : %f1.4", coef(relation2)[5])

sprintf("OPS : %f1.4", coef(relation2)[6])

# Calculate expected RBIs based on stats

# Evan Longoria

# RBIs AVG HR OBP SLG OPS

# 86 .261 20 .313 .424 .737

RBIGuess = -5.05 + (372.96 * .261) + (2.56 * 20) +

(-5.41 * .313) + (-167.37 * .424)

RBIGuess

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