More R

Question 1

What is R

Answer 1

a programming language used for data analytics, statistics

Question 2

how is it similar to python

Answer 2

it is an interpreted language

Question 3

object names rules

Answer 3

letters, names and underscores only

Question 4

data structures in r

Answer 4

vector, list one dimension. matrix, dataframe, 2 dimension

Question 5

how to index vectors

Answer 5

vector[2]. or vector[c(2,3)]

Question 6

format of matrices

Answer 6

mymatrix = matrix(vector, nrow = x, ncol = y, byrow = False, dimnames = list(c(“row names”), c(“column names”)))

Question 7

how to index matrices

Answer 7

y[,4] # 4th column of matrix
y[3,] # 3rd row of matrix
y[2:4,1:3] # rows 2,3,4 of columns 1,2,3

Question 8

are lists ordered

Answer 8

yes

Question 9

can lists contain elements of different types

Answer 9

yes

Question 10

how to index lists

Answer 10

thisisalist[[2]]

Question 11

do all columns in the matrix have to have the same mode (numeric, integer, factor, text)

Answer 11

Yes

Question 12

can different columns in the data frame have different modes

Answer 12

yes

Question 13

what is the code for dataframes

Answer 13

mydata = data.frame(vector1, vector2, vector3)

Question 14

how to index dataframes

Answer 14

dataframe[1:3, 2:4]
mydata[c(“ID”, “Passed”)] (the column names)
mydata$X1 (the column X1)