▸ R (Programming Language)  LinkedIn Skill Assessment Quiz Solutions
Recommended R Programming Courses:
 Udemy: R Programming  R Language for Absolute Beginners
 Udemy: R Programming AZ™: R For Data Science With Real Exercises!
 Udemy: R Programming: Advanced Analytics In R For Data Science
 Coursera: Data Science: Foundations using R Specialization
 Coursera: Statistics with R Specialization
 LinkedIn: Master R for Data Science
 edX: R Programming Fundamentals
 edureka: Data Analytics with R Certification Training
 Eduonix: R Programming for Beginners

How does a matrix differ from a data frame?
 A matrix may contain numeric values only.
 A matrix must not be singular.
 A data frame may contain variables that have different modes.
 A data frame may contain variables of different lengths.

What value does this statement return?
unclass(as.Date("19710101"))
 1
 365
 4
 12

What do you use to take an object such as a data frame out of the workspace?
 remove()
 erase()
 detach()
 delete()

Review the following code. What is the result of line 3?
xvect<c(1,2,3) xvect[2] < "2" xvect
 [1] 1 2 3
 [1] “1” 2 “3”
 [1] “1” “2” "3"
 [1] 7 9

The variable height is a numeric vector in the code below. Which statement returns the value 35?

height(length(height))

height[length(height)]

height[length[height]]

height(5)


In the image below, the data frame is named rates. The statement
sd(rates[, 2])
returns 39. As what does R regard Ellen’s product ratings?
 sample with replacement
 population
 trimmed sample
 sample < not sure

Which choice does R regard as an acceptable name for a variable?

Var_A!

\_VarA

.2Var_A

Var2_A


What is the principal difference between an array and a matrix?
 A matrix has two dimensions, while an array can have three or more dimensions.
 An array is a subtype of the data frame, while a matrix is a separate type entirely.
 A matrix can have columns of different lengths, but an array’s columns must all be the same length.
 A matrix may contain numeric values only, while an array can mix different types of values.

Which is not a property of lists and vectors?
 type
 length
 attributes
 scalar

In the image below, the data frame on lines 1 through 4 is names StDf. State and Capital are both factors. Which statement returns the results shown on lines 6 and 7?
 StDf[1:2,3]
 StDf[1:2,1]
 StDf[1:2,]
 StDf[1,2,]

Which function displays the first five rows of the data frame named pizza?
 BOF(pizza, 5)
 first(pizza, 5)
 top(pizza, 5)
 head(pizza, 5)

You accidentally display a large data frame on the R console, losing all the statements you entered during the current session. What is the best way to get the prior 25 statements back?
 console(25)
 console(reverse=TRUE)
 history()
 history(max.show = 25)

d.pizza is a data frame. It’s column named temperature contains only numbers. If u extract temperature using the [] accessors, its class defaults to numeric. How can you access temperature so that it retains the class of data.frame?
> class( d.pizza[ , "temperature" ] ) > "numeric"

class( d.pizza( , "temperature" ) )

class( d.pizza[ , "temperature" ] )

class( d.pizza$temperature )

class( d.pizza[ , "temperature", drop=F ] )


What does c contain?
a < c(3,3,6.5,8) b < c(7,2,5.5,10) c < a < b
 [1] NaN
 [1] 4
 [1] 4 1 1 2
 [1] TRUE FALSE FALSE TRUE

Review the statements below. Does the use of the dim function change the class of y, and if so what is y’s new class?
> y < 1:9 > dim(y) < c(3,3)
 No, y’s new class is “array”.
 Yes, y’s new class is “matrix”.
 No, y’s new class is “vector”.
 Yes, y’s new class is “integer”.

What is
mydf$y
in this code?
mydf < data.frame(x=1:3, y=c("a","b","c"), stringAsFactors=FALSE)
 list
 string
 factor
 character vector

How does a vector differ from a list?
 Vectors are used only for numeric data, while list are useful for both numeric and string data.
 Vectors and lists are the same thing and can be used interchangeably.
 A vector contains items of a single data type, while a list can contain items of different data types.
 Vectors are like arrays, while lists are like data frames.

What statement shows the objects on your workspace?
 list.objects()
 print.objects()
 getws()
 ls()

What function joins two or more column vectors to form a data frame?
 rbind()
 cbind()
 bind()
 coerce()

Review line 1 below. What does the statement in line 2 return?
1 mylist < list(1,2,"C",4,5) 2 unlist(mylist)
 [1] 1 2 4 5
 “C”
 [1] “1” “2” “C” “4” "5"
 [1] 1 2 C 4 5

What is the value of y in this code?
x < NA y < x/1
 Inf
 Null
 NaN
 NA

Two variable in the mydata data frame are named Var1 and Var2. How do you tell a bivariate function, such as cor.test, which two variables you want to analyze?

cor.test(Var1 ~ Var2)

cor.test(mydata$(Var1,Var2))

cor.test(mydata$Var1,mydata$Var2)

cor.test(Var1,Var2, mydata)


A data frame named d.pizza is part of the DescTools package. A statement is missing from the following R code and an error is therefore likely to occur. Which statement is missing?
library(DescTools) deliver < aggregate(count,by=list(area,driver), FUN=mean) print(deliver)

attach(d.pizza)

summarize(deliver)

mean < rbind(d.pizza,count)

deliver[!complete.cases(deliver),]


How to name rows and columns in DataFrames and Matrices F in R?
 data frame: names() and rownames() matrix: colnames() and row.names()
 data frame: names() and row.names() matrix: dimnames() (not sure)
 data frame: colnames() and row.names() matrix: names() and rownames()
 data frame: colnames() and rownames() matrix: names() and row.names()

Which set of two statementsfollowed by the cbind() functionresults in a data frame named vbound?

A
v1<list(1,2,3) v2<list(c(4,5,6)) vbound<cbind(v1,v2)

B
v1<c(1,2,3) v2<list(4,5,6)) vbound<cbind(v1,v2)

C
v1<c(1,2,3) v2<c(4,5,6)) vbound<cbind(v1,v2)


ournames is a character vector. What values does the statement below return to Cpeople?
Cpeople < ournames %in% grep("^C", ournames, value=TRUE)
 records where the first character is a C
 any record with a value containing a C
 TRUE or FALSE, depending on whether any character in ournames is C
 TRUE or FALSE values, depending on whether the first character in an ournames record is C

What is the value of names(v[4])?
v < 1:3 names(v) < c("a", "b", "c") v[4] < 4
 ""
 d
 NULL
 NA

Which of the following statements doesn’t yield the code output below. Review the following code. What is the result of line 3?
x < c(1, 2, 3, 4) Output: [1] 2 3 4
 x[c(2, 3, 4)]
 x[1]
 x[c(1, 0, 0, 0)]
 x[c(1, 2, 3, 4)]

Given DFMerged < merge(DF1, DF2) and the image below, how manu rows are in DFMerged?
DF1(data frame 1): DF2(data frame 2): VarA VarB VarA VarD 1 1 2 1 18 21 2 4 5 2 19 22 3 7 8 3 20 23
 6
 9
 3
 0
CREDITS: (Source)
&
Click here to see solutions for all Machine Learning Coursera Assignments.
&
Click here to see more codes for Raspberry Pi 3 and similar Family.
&
Click here to see more codes for NodeMCU ESP8266 and similar Family.
&
Click here to see more codes for Arduino Mega (ATMega 2560) and similar Family.
Feel free to ask doubts in the comment section. I will try my best to answer it.
If you find this helpful by any mean like, comment and share the post.
This is the simplest way to encourage me to keep doing such work.
 APDaga DumpBox