R

Question 1

How to check the type?

Answer 1

is. numeric(MyFirstVector)
is. integer(MyFirstVector)
is. double(MyFirstVector)
is. character(v3)

Question 2

How to create a vector?

Answer 2

x – c(1, 5, 4, 9, 0)
x – c(1, 5.4, TRUE, “hello”)
x – 1:7
seq(1, 3, by=0.2)

Question 3

Brackets

w[-1]

Answer 3

x[c(2, 4)] # access 2nd and 4th element

w[-1] # access all but 1st element

Question 4

for loop

Answer 4

for (x in 1:10) {
print(x)
}

fruits

Question 5

type

Answer 5

typeof()

Question 6

How to get some info. about functions?

Answer 6

?rnorm()

Question 7

Install and activate a package

Answer 7

install.packages(“ggplot2”)

library(ggplot2) #activate

Question 8

Matrix Indexation

Answer 8

[2,3]
[2,]
[.3]

Question 9

How to remove a vector?

How to remove a dataframe?

Answer 9

rm(vector1, vector2,vector3)

rm(mydf)

Question 10

Building a matrix, 3 ways

Answer 10

rbind()

cbind()

matrix(my.data, 4, 5) , byrow =T

Question 11

How to name a vector? +remove name

Answer 11

vector – c(“John Doe”, “poker player”)
names(vector) – c(“Name”, “Profession”)

unname(vector)

Question 12

How to name rows and cols of a matrix?

Answer 12

rownames(baskets.team) – c(“Granny”, “Geraldine”)

colnames(baskets.team) – c(“1st”, “2nd”, “3th”, “4th”, “5th”, “6th”)

Question 13

matplot

legend

Answer 13

matplot(t(FieldGoals), type=”b”, pch=15:18, col=c(1:4,6))

legend(“bottomleft”, inset=0.01, legend = Players, pch=15:18, col=c(1:4,6), horiz=F)

Question 14

Subsetting

Answer 14

Games[1:3,6:10]
Games[c(1,10),]
Games[,c(“2008”,”2009”)]

Games[1,]
Games[1,,drop=F]

Question 15

Create a function and set default values

Answer 15

myplot

Question 16

Main diff between matrix and dataframe?

Answer 16

All elements of the matrix have same type

Question 17

Select it manually and read a csv file

Answer 17

stats

Question 18

Set working directory

Answer 18

getwd()

setwd(“C:/Users/266507/OneDrive - American Airlines, Inc/Documents/R”)

Question 19

Read a csv file

Answer 19

stats

Question 20

find no. of rows and columns:

Answer 20

nrow(stats)

ncol(stats)

Question 21

head and tail:

Answer 21

head(stats, n=10)

tail(stats)

Question 22

summary of the data:

Answer 22

str(stats)

summary(stats)

Question 23

Using the $ sign:

Answer 23

stats$Country.Name

stats[,”Country.Name”]

stats$Country.Name[2]

Question 24

Categories:

Answer 24

levels(stats$Country.Name)

Question 25

A diff between Matrix and DataFrame:

Answer 25

When we get one row of a matrix, it become a vector but it’s not the case in DataFrame
But it’s gonna be a vector when we get a col in a dataframe

Question 26

How to check if it’s a dataframe

Answer 26

is.data.frame(stats[1,])

Question 27

How to preserve a col of a dataframe as a dataframe when subsetting:

Answer 27

stats[,1,drop=F]

Question 28

Add and remove a col to a dataframe

Answer 28

stats$MyCalc

Question 29

Filtering dataframes

Answer 29

stats[stats$Birth.rate>40 & stats$Internet.users<2, ]

stats[stats$Income.Group == “High income”, ]

Question 30

qplot

Answer 30

qplot(data=stats, x=Internet.users)

qplot(data=stats, x=Income.Group, y=Birth.rate)

qplot(data=stats, x=Income.Group, y=Birth.rate, size=I(3), color=I(“blue”))

qplot(data=stats, x=Internet.users, y=Birth.rate, size=I(5), color=Income.Group)

qplot(data=stats, x=Income.Group, y=Birth.rate, geom=”boxplot”)

Question 31

Creating DataFrames

Answer 31

mydf

Question 32

Merging Data Frames

Answer 32

merged

Question 33

Change the shape on qplot

Answer 33

qplot(data=merged, x=Internet.users, y=Birth.rate, color=Region, size=I(5), shape=I(19))

Question 34

Control the transparency on qplot

Answer 34

qplot(data=merged, x=Internet.users, y=Birth.rate, color=Region, size=I(5), shape=I(19), alpha=I(0.6))

Question 35

Set the title in qplot

Answer 35

qplot(data=merged, x=Internet.users, y=Birth.rate, color=Region, size=I(5), shape=I(19), alpha=I(0.6), main=”Birth Rate vs Internet Users”)