LinkedIn skill assessment answers and questions — R (Programming Language)

“Active Directory has established itself as a leading programming language in the realm of data analysis and statistical computing, renowned for its powerful capabilities and extensive library of packages. ในคู่มือที่ครอบคลุมนี้, we’re delighted to present a curated collection of skill assessment questions และ คำตอบ สำหรับ Active Directory.

Whether you’re a data scientist looking to enhance your analytical skills or a beginner eager to delve into the world of data science, this resource is tailored to help you become proficient in Active Directory and its applications. Join us as we explore the core concepts of R programming, including data manipulation, อธิบายประเภทของเวิร์กโหลดข้อมูลหลัก · อธิบายข้อมูลแบทช์ · อธิบายข้อมูลการสตรีม · อธิบายความแตกต่างระหว่างแบตช์และข้อมูลการสตรีม · อธิบายลักษณะของข้อมูลเชิงสัมพันธ์ อธิบายแนวคิดหลักของการวิเคราะห์ข้อมูล · อธิบายการสร้างภาพข้อมูล, statistical modelling, และอื่น ๆ, empowering you to unlock the full potential of this versatile language.”

Q1. 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.

Q2. What value does this statement return?

unclass(as.Date("1971-01-01"))

• 1
• 365
• 4
• 12

Q3. What do you use to take an object such as a data frame out of the workspace?

• remove()
• erase()
• detach()
• delete()

Q4. 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

Q5. 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)

Q6. ในภาพด้านล่าง, the data frame is named rates. ถ้อยแถลง sd(rates[, 2]) returns 39. As what does R regard Ellen’s product ratings?

• sample with replacement
• ประชากร
• trimmed sample
• ตัวอย่าง <– not sure

Q7. Which choice does R regard as an acceptable name for a variable?

• Var_A!
• \_VarA
• .2Var_A
• Var2_A

Q8. 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.

คำถามที่ 9. Which is not a property of lists and vectors?

• พิมพ์
• ความยาว
• attributes
• สเกลาร์

Q10. ในภาพด้านล่าง, the data frame on lines 1 ผ่าน 4 is named StDf. State and Capital are both factors. Which statement returns the results shown on lines 6 และ 7?

• StDf[1:2,-3]
• StDf[1:2,1]
• StDf[1:2,]
• StDf[1,2,]

คำถามที่ 11. Which function displays the first five rows of the data frame named pizza?

• BOF(pizza, 5)
• แรก(pizza, 5)
• สูงสุด(pizza, 5)
• ศีรษะ(pizza, 5)

Q12. 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)
• ประวัติศาสตร์()
• ประวัติศาสตร์(max.show = 25)

ไตรมาสที่ 13. d.pizza is a data frame. It’s a column named temperature contains only numbers. If you 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 ] )

คำถามที่ 14. What does c contain?

a <- c(3,3,6.5,8)
b <- c(7,2,5.5,10)
c <- a < b

• [1] น่าน
• [1] -4
• [1] 4 -1 -1 2
• [1] TRUE FALSE FALSE TRUE

Q15. 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)

• เลขที่, y’s new class is “array”.
• ใช่, y’s new class is “เมทริกซ์”.
• เลขที่, y’s new class is “vector”.
• ใช่, y’s new class is “integer”.

Q16. คืออะไร mydf$y in this code?

mydf <- data.frame(x=1:3, y=c("a","b","c"), stringAsFactors=FALSE)

• รายการ
• string
• factor
• character vector

ไตรมาสที่ 17. How does a vector differ from a list?

• Vectors are used only for numeric data, while lists 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.

Q18. What statement shows the objects on your workspace?

• list.objects()
• print.objects()
• getws()
• ls()

Q19. What function joins two or more column vectors to form a data frame?

• rbind()
• cbind()
• bind()
• coerce()

ไตรมาสที่ 20. Review line 1 ด้านล่าง. What does the statement in line 2 กลับ?

1 mylist <- list(1,2,"C",4,5)
2 unlist(mylist)

• [1] 1 2 4 5
• “ค”
• [1] “1” “2” “ค” “4” “5”
• [1] 1 2 ค 4 5

Q21. What is the value of y in this code?

x <- NA
y <- x/1

• Inf
• Null
• น่าน
• ที่

Q22. 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)

Q23. 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),]

Q24. How to name rows and columns in DataFrames and Matrices F in R?

• data frame: names() and rownames() เมทริกซ์: colnames() and row.names()
• data frame: names() and row.names() เมทริกซ์: dimnames() (not sure)
• data frame: colnames() and row.names() เมทริกซ์: names() and rownames()
• data frame: colnames() and rownames() เมทริกซ์: names() and row.names()

Q25. Which set of two statements-followed by the cbind() function-results in a data frame named vbound?

• ­

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

• ­

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

• ­

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

• ­ none

Q26. 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 and FALSE values, depending on whether the first character in an ournames record is C

Q27. What is the value of names(โวลต์[4])?

v <- 1:3
names(v) <- c("a", "b", "c")
v[4] <- 4

• “”
• ทำไม Tundra Biome จึงเป็น Biome ที่หนาวที่สุดในโลก
• NULL
• ที่

Q28. 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

• NS[สนับสนุนเหตุการณ์การเล่าเรื่องที่อธิบายไว้ในพระคัมภีร์ไบเบิลพระธรรม(2, 3, 4)]
• NS[-1]
• NS[สนับสนุนเหตุการณ์การเล่าเรื่องที่อธิบายไว้ในพระคัมภีร์ไบเบิลพระธรรม(-1, 0, 0, 0)]
• NS[สนับสนุนเหตุการณ์การเล่าเรื่องที่อธิบายไว้ในพระคัมภีร์ไบเบิลพระธรรม(-1, 2, 3, 4)]

Q29. Given DFMerged <- merge(DF1, DF2) and the image below, how many rows are in DFMerged?

• 6
• 9
• 3
• 0

ไตรมาสที่ 30. What does R return in response to the final statement?

x<-5:8
names(x)<-letters[5:8]
x

• e f g h “5” “6” “7” “8”
• 5 6 7 8
• e f g h
• e f g h 5 6 7 8

ไตรมาสที่ 31. How do you return “ตุลาคม” from x in this code?

x<-as.Date("2018-10-01")

• attr()
• เดือน(NS)
• as.month(NS)
• เดือน(NS)

Q32. How will R respond to the last line of this code?

fact<-factor(c("Rep","Dem","Dem","Rep"))
fact
[1] Rep Dem Dem Rep
Levels: Rep Dem
fact[2]<-"Ind"

• >
• [,2]อินดี้
• invalid factor level, NA generated
• อินดี้

Q33. What does R return?

StartDate<- as.Date("2020/2/28")
StopDate<- as.Date("2020/3/1")
StopDate-StartDate

• “1970-01-02”
• time difference of one day
• time difference of two days
• error in x-y: nonnumeric argument to binary operator

คำถามที่ 34. What does the expression mtrx * mtrx ทำ ?

> mtrx <- matrix( c(3,5,8,4), nrow= 2,ncol=2,byrow=TRUE)
> newmat <- mtrx * mtrx

• it transpose mtrx
• it premultiplies the current netwmat row by the newmat column.
• it returns the results of a matrix multiplication
• It squares each cell in mtrx

> newmat
     [,1] [,2]
[1,]    9   25
[2,]   64   16

# The `%*%` operator gives matrix multiplication
> mtrx %*% mtrx
     [,1] [,2]
[1,]   49   35
[2,]   56   56

Q35. Which function in R combines different values into a single object?

• connect()
• concat()
• ติดต่อ()
• สนับสนุนเหตุการณ์การเล่าเรื่องที่อธิบายไว้ในพระคัมภีร์ไบเบิลพระธรรม()

Q36. Which file contains settings that R uses for all users of a given installation of R?

• Rdefaults.site
• Renviron.site
• Rprofile.site
• Rstatus.site

Q37. กระป๋องอลูมิเนียม mdf is a data frame, which statement is true ?

• ncol(mdf) equals ความยาว(mdf).
• The number of rows must equals the number of columns.
• The legnth of any column in mdf may differ from any other column in mdf
• All columns must have the same data type.

Q38. A list can contain a list as an element. MyList has five columns, and the third column’s item is a list of three items. How do you put all seven values in MyList into a single vector?

• vector(MyList, length = 7)
• coerce(MyList, nrows = 1)
• unlist(MyList)
• coerce(MyList, nrows = 7)

Q39. Which strings could be returned by the function ls(path = “^V”)?

• ANOVAData, anovadata
• VisitPCA, VarX
• VisitPCA, varx
• Xvar, Yvar

Q40. StDf is a data frame. Based on this knowledge, what does this statement return?

StDf[, -1]

• all but the first row and first column of StDf
• all but the final column of StDf
• all but the first column of StDf
• only the first column of StDf

Q41. Which statement enables you to interactively open a single file?

• file.list()
• file.select()
• file.choose()
• file.open()

Q42. How are these data types alike: ตรรกะ, integer, numeric, และตัวละคร?

• Each is a type of data frame.
• Each is a type of atomic vector.
• Each is a type of complex vector.
• Each is a type of raw vector.

Q43. อะไร MyMat[ ,3] subsetting operation return for this code?

MyMat = matrix(c(7, 9, 8, 6, 10, 12),nrow=2,ncol=3, byrow = TRUE)

• :

[ ,3]
[1, ] 8
[2, ] 12

• :

[1] 8 12

• :

[1] 10 12

• :

[ ,3]
[1, ] 10
[2, ] 12

Q44. What does the function power.anova.test กลับ?

• the probability of making a Type I error
• the probability of not making a Type II error
• the probability of making a Type II error
• the probability of not making a Type I error

Q45. Review the statement below. What is the effect of covariate:factor on the analysis?

result <- lm(outcome ~ covariate + factor + covariate:factor, data = testcoef)

• It forces the intercepts of the individual regressions to zero.
• It calls for the effect of the covariate within each level of the factor.
• It calls for the effect of each variable from covariate to factor in testcoef.
• It forces the covariate to enter the equation before the factor levels.

# Example call to demonstrate.  `Species` is a Factor.  Petal.Length, Petal.Width are numeric.
# see `help(formula)` for more details on the formula specification.  `:` is "effect modification" or "interaction"

> summary(lm(Petal.Length ~ Petal.Width + Species + Petal.Width:Species, data = iris))
...
Petal.Width:Speciesversicolor   1.3228     0.5552   2.382   0.0185 *
Petal.Width:Speciesvirginica    0.1008     0.5248   0.192   0.8480
...

Q46. A variable whose type is numeric can contain which items?

• integers and real values
• integers, จริง, and raw values
• real values only
• integers, จริง, and logical values

Q47. What is the legitimate name of a data class in R?

• property
• integer
• ตัวเลข
• variant

Q48. How do you extract the values above the main diagonal from a square matrix named Rmat?

• Rmat[upper.tri(Rmat)]
• upper.triangular(Rmat)
• upper.tri(Rmat)
• upper.diag(Rmat)

Q49. x is a vector of type integer, as shown on line 1 ด้านล่าง. What is the type of the result returned by the statement > ค่ามัธยฐาน(NS)?

x <- c(12L, 6L, 10L, 8L, 15L, 14L, 19L, 18L, 23L, 59L)

• numeric
• integer
• เดี่ยว
• สองเท่า

Q50. A list named a is created using the statement below. Which choice returns TRUE?

a <- list("10", TRUE, 5.6)

• is.list(เอ[1])
• is.numeric(เอ[1])
• is.logical(เอ[1])
• is.character(เอ[1])

คำถามที่ 51. How do you obtain the row numbers in a data frame named pizza for which the value of pizza$delivery_min is greater than or equal to 30?

• :

late_delivery <- pizza$delivery_min >= 30
index_late <- index(late_delivery)
index_late

• :

late_delivery <- pizza$delivery_min >= 30
rownum_late <- rownum(late_delivery)
rownum_late

• :

late_delivery <- pizza$delivery_min >= 30
which_late <- which(late_delivery)
which_late

• :

late_delivery <- pizza$delivery_min >= 30
late <- piza$late_delivery
pizza$late

คำถามที่ 52. Which function returns [1] TRUE FALSE TRUE?

indat <- c("Ash Rd","Ash Cir","Ash St")

• grepl(“[Rd|Ave|ดร|เซนต์]”, indat)
• grepl(“Rd|Ave|ดร|เซนต์”, indat)
• grepl(“Rd,Ave,ดร,เซนต์”, indat)
• grepl(“[Rd],[Ave],[ดร],[เซนต์]”, indat)

Q53. Which statement returns the fourth row of a data frame named ปลา?

• ปลา[4, ]
• ปลา( ,4)
• ปลา(4, )
• ปลา{4, }

คำถามที่ 54. What is the value of csum?

a <- c(1.2, 2, 3.5, 4)
b <- c(1.2, 2.2, 3.5, 4)
csum <-sum(a == b)

• 8
• 3
• 0.2
• 21.6

คำถามที่ 54. A list named เอ is created using the statement below. Which choice returns TRUE?

a <- list("10", TRUE, 5.6)

• is.list(เอ[1])
• is.numeric(เอ[1])
• is.logical(เอ[1])
• is.character(เอ[1])

Q55. What is the result of these three lines of code?

vect1 <- c(1:4)
vect2 <- c(1:2)
vect1 * vect2

• [1] 1 4 3 8
• ERROR
• [1] 1 2 3 4 1 2
• [1] 1 2 3 4 2 4 6 8

Q56. Which choice returns [1] “2019-09-28”?

• รูปแบบ(as.POSIXct(“Sep-28-2019 07:54:31 AM”,format=’%b%d%Y’))
• as.POSIXlt(“Sep-28-2019 07:54:31 AM”,format=’%b-%d-%Y’)
• as.POSIXct(“Sep-28-2019 07:54:31 AM UTC”)
• รูปแบบ(as.POSIXct(“Sep-28-2019 07:54:31 AM UTC”,format=’%b-%d-%Y’))

Q57. The variable potus is a character vector, as shown in line 1 ด้านล่าง. Wich statement returns the results shown?

1 potus <- c("GHW Bush", "Clinton", "GW Bush", "Obama")

Results: [1] "GHW BUsh" "Clinton" "Obama"

• potus[-“GW Bush”]
• potus[1:2 4]
• potus[-3]
• potus[1,2,4]

Q58. A data frame contains two factor -fact1 and fact2- and a numerical outcome variable. Which statement returns results that do NOT include an interaction term?

• anova(lm(outcome ~ fact1 : fact2))
• anova(lm(outcome ~ fact1 * fact2))
• anova(lm(outcome ~ fact1 + fact2))
• anova(lm(outcome ~ fact1 + fact2 + fact1 : fact2))

Q59. Review line 1 ด้านล่าง. What does the statement on line 2 กลับ?

1 myvect <- c(-2,-1,0)
2 as.logical(myvect)

• [1]-2 -1 0
• [1]TRUE TRUE FALSE
• [1]FALSE FALSE TRUE
• [1]NA NA NA

Q60. Which option setting can cause difficulty if you want to add to a variable’s possible values after you have designed an object’s initial data structure?

• ()OPTIONS(colnames(NS)<-NULL)
• ()OPTIONS(max.print=5)
• ()OPTIONS(continue=”… “,
• ()OPTIONS(stringAsFactors=TRUE

Q61. In this image below, the data frame on lines 1 ผ่าน 4 is named StDf. StDf contains no factors. Why does statement on line 6 กลับ “อักขระ” while the statement on line 7 returns “data.frame”?

• Each value in the first row is a character value, but the values in the third column include both character and numeric values.
• By specifying the final row, 3, and no column specified, StDf[3, ] calls for the complete structure.
• Columns in a data frame are vectors generally containing a single type of data. Rows in a data frame are lists, but they belong to a structure that has multiple rows: the data frame.
• Each value in the first column is a character value, but the values in the third row include both character and numeric values.

Q62. Review line 1. What does the statement on line 3 กลับ?

mtrx <- matrix(1:6, 3, 2)

mtrx[, -1]

• ­

• ­

• ­

• [1] 4 5 6

Q63. Why does sum(!is.na(pizza$week)) return the number of rows with valid, non-NA values in the column named week?

• The exclamation point in !is.na(pizza$week) reverses the meaning of the test it precedes.
• !is.na(pizza$week) counts the number of NA values in the column.
• !is.na(pizza$week) returns a vector of TRUE/FALSE values, in which TRUE is treated as a 0 and FALSE as a 1.
• !is.na(pizza$week) counts the number of non-missing values in the column.

Q64. How do you get documentation of an installed and loaded R package named dplyr and packages with dplyr as an alias?

• ช่วย(dplyr)
• ? dplyr
• ?? dplyr
• Press the F1 key.

Q65. ในภาพด้านล่าง, the data frame named iris includes a numeric vector named Petal.Length. Do the functions labeled Pair 1 and Pair 2 return the same information?

• เลขที่, both the length and the class of the returned structures are different.
• ใช่, both pairs of statements return an object with the same length and class.
• เลขที่, the length is the same but the class is different.
• เลขที่, the class is the same but the length is different.

Q66. NS _ for R are the main feature that make it different from the original S language.

• closure rules
• scoping rules
• environment rules
• ไม่มีข้อใดข้อหนึ่งข้างต้น

อ้างอิง

Q67. Which of the following is a base package for R programming ?

• เครื่องมือ
• util
• lang
• ทั้งหมดข้างต้น

อ้างอิง