Question

# How do you select the the vector c(7, 8, 9) using the following four approaches

# (1) Using the [[]] operator once and only once # Your code below

(2) Using the [] operator once # Your code below

(3) Using the $ operator # Your code below

(4) Using a column vector name without using the $ operator # Your code below

Answer 1

ANSWER:

• I have provided the properly commented code in both text and image format so you can easily copy the code as well as check for correct indentation.
• I have provided the output image of the code so you can easily cross-check for the correct output of the code.
• Have a nice and healthy day!!

CODE TEXT

# defining a dataframe with columname value and c(7,8,9)
df <- data.frame(value=c(7,8,9))
# (1) Using the [[]] operator once and only once
df[[1]]
# (2) Using the [] operator once\
df[,1]
# (3) Using the $ operator
df$value
# (4) Using a column vector name without using the $ operator
df[,"value"]

CODE IMAGE

OUTPUT IMAGE