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LinkedIn skill assessment answers and questions — R (لغة برمجة)

الرئيسية/ LinkedIn skill assessment answers and questions — R (لغة برمجة)

LinkedIn skill assessment answers and questions — R (لغة برمجة)

شهر فبراير 23, 2024 ينكدين , ممارسة س&ا ‫0 تعليق 61 مشاهدات

“R 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. في هذا الدليل الشامل, we’re delighted to present a curated collection of أسئلة تقييم المهارات و الإجابات إلى عن على R.

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 R and its applications. Join us as we explore the core concepts of R programming, including data manipulation, التصور, statistical modelling, و اكثر, 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()
  • يمسح()

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. في الصورة أدناه, the data frame is named rates. البيان sd(rates[, 2]) returns 39. As what does R regard Ellen’s product ratings?

صورة

  • sample with replacement
  • تعداد السكان
  • trimmed sample
  • عينة <– 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.

Q9. Which is not a property of lists and vectors?

  • نوع
  • الطول
  • attributes
  • العددية

Q10. في الصورة أدناه, the data frame on lines 1 عبر 4 is named StDf. State and Capital are both factors. Which statement returns the results shown on lines 6 و 7?

صورة

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

سوف تحتاج إلى تحقيق ما لا يقل عن. Which function displays the first five rows of the data frame named pizza?

  • BOF(pizza, 5)
  • أول(pizza, 5)
  • أعلى(pizza, 5)
  • رئيس(pizza, 5)

س 12. 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)
  • التاريخ()
  • التاريخ(max.show = 25)

Q13. 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 ] )

س 14. 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

س 15. 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)
  • لا, y’s new class is “مجموعة مصفوفة”.
  • نعم فعلا, y’s new class is “مصفوفة”.
  • لا, y’s new class is “vector”.
  • نعم فعلا, y’s new class is “integer”.

س 16. ما هو mydf$y in this code?

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

  • قائمة
  • خيط
  • factor
  • character vector

Q17. 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.

س 18. What statement shows the objects on your workspace?

  • list.objects()
  • print.objects()
  • getws()
  • ليرة سورية()

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

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

س 20. Review line 1 أدناه. What does the statement in line 2 يعود?

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

س 21. What is the value of y in this code?

x <- NA
y <- x/1
  • Inf
  • Null
  • NaN
  • NA

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),]

س 24. How to name rows and columns in DataFrames and Matrices F in R?

  • data frame: names() and rownames() مصفوفة: أسماء الأعمدة() and row.names()
  • data frame: names() and row.names() مصفوفة: dimnames() (not sure)
  • data frame: أسماء الأعمدة() and row.names() مصفوفة: names() and rownames()
  • data frame: أسماء الأعمدة() and rownames() مصفوفة: 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

س 26. 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(الخامس[4])?

v <- 1:3
names(v) <- c("a", "b", "c")
v[4] <- 4
  • “”
  • د
  • NULL
  • NA

س 28. 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
  • س[ج(2, 3, 4)]
  • س[-1]
  • س[ج(-1, 0, 0, 0)]
  • س[ج(-1, 2, 3, 4)]

س 29. Given DFMerged <- merge(DF1, DF2) and the image below, how many rows are in DFMerged?

صورة

  • 6
  • 9
  • 3
  • 0

Q30. 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

س 31. How do you return “شهر اكتوبر” from x in this code?

x<-as.Date("2018-10-01")
  • attr()
  • الشهور(س)
  • as.month(س)
  • شهر(س)

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]دائرة الهجرة والجنسية
  • invalid factor level, NA generated
  • دائرة الهجرة والجنسية

على ___. 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

س 34. What does the expression mtrx * mtrx فعل ?

> 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

تتم محاذاة كل طبقة وهذه كلها في نفس الوقت. Which function in R combines different values into a single object?

  • connect()
  • concat()
  • اتصل()
  • ج()

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. إذا mdf is a data frame, which statement is true ?

  • ncol(mdf) equals الطول(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

س 40. 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

س 41. Which statement enables you to interactively open a single file?

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

س 42. How are these data types alike: منطقي, integer, numeric, وشخصية?

  • 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.

س 43. ماذا يكون ال 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

س 44. What does the function power.anova.test يعود?

  • 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

س 45. 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
...

س 46. A variable whose type is numeric can contain which items?

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

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

  • ملكية
  • integer
  • رقم
  • variant

س 48. 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 أدناه. What is the type of the result returned by the statement > الوسيط(س)?

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

  • numeric
  • integer
  • المدير العام الحالي هو د
  • مزدوج

س 50. A list named a is created using the statement below. Which choice returns TRUE?

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

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

س 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

Q52. Which function returns [1] TRUE FALSE TRUE?

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

  • grepl(“[Rd|Ave|دكتور|سانت]”, indat)
  • grepl(“Rd|Ave|دكتور|سانت”, indat)
  • grepl(“Rd,Ave,دكتور,سانت”, indat)
  • grepl(“[Rd],[Ave],[دكتور],[سانت]”, indat)

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

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

س 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

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

a <- list("10", TRUE, 5.6)
  • is.list(ا[1])
  • is.numeric(ا[1])
  • is.logical(ا[1])
  • is.character(ا[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

س 56. Which choice returns [1] “2019-09-28”?

  • شكل(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”)
  • شكل(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 أدناه. 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]

س 58. 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))

س 59. Review line 1 أدناه. What does the statement on line 2 يعود?

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

س 60. 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(أسماء الأعمدة(س)<-NULL)
  • ()OPTIONS(max.print=5)
  • ()OPTIONS(continue=”… “,
  • ()OPTIONS(stringAsFactors=TRUE

س 61. In this image below, the data frame on lines 1 عبر 4 is named StDf. StDf contains no factors. Why does statement on line 6 يعود “حرف” while the statement on line 7 returns “data.frame”?

صورة

  • 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.

س 62. Review line 1. What does the statement on line 3 يعود?

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

mtrx[, -1]

صورة

  • ­

  • ­

  • ­

  • [1] 4 5 6

س 63. 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.

س 64. How do you get documentation of an installed and loaded R package named dplyr and packages with dplyr as an alias?

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

س 65. في الصورة أدناه, 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?

صورة

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

س 66. ال _ for R are the main feature that make it different from the original S language.

  • closure rules
  • scoping rules
  • environment rules
  • لا شيء مما بالأعلى

مرجع

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

  • أدوات
  • util
  • lang
  • كل ما ورداعلاه

مرجع

مؤلف

  • هيلين باسي

    مرحبا, I'm Helena, كاتب مدونة شغوف بنشر محتويات ثاقبة في مجال التعليم. أعتقد أن التعليم هو مفتاح التنمية الشخصية والاجتماعية, وأريد أن أشارك معرفتي وخبرتي مع المتعلمين من جميع الأعمار والخلفيات. على مدونتي, ستجد مقالات حول موضوعات مثل استراتيجيات التعلم, التعليم عبر الإنترنت, إرشاد مهني, و اكثر. وأرحب أيضًا بتعليقات واقتراحات القراء, لذلك لا تتردد في ترك تعليق أو الاتصال بي في أي وقت. أتمنى أن تستمتع بقراءة مدونتي وتجدها مفيدة وملهمة.

    مشاهدة جميع المشاركات
هيلينا بينارد

عن هيلين باسي

مرحبا, I'm Helena, كاتب مدونة شغوف بنشر محتويات ثاقبة في مجال التعليم. أعتقد أن التعليم هو مفتاح التنمية الشخصية والاجتماعية, وأريد أن أشارك معرفتي وخبرتي مع المتعلمين من جميع الأعمار والخلفيات. على مدونتي, ستجد مقالات حول موضوعات مثل استراتيجيات التعلم, التعليم عبر الإنترنت, إرشاد مهني, و اكثر. وأرحب أيضًا بتعليقات واقتراحات القراء, لذلك لا تتردد في ترك تعليق أو الاتصال بي في أي وقت. أتمنى أن تستمتع بقراءة مدونتي وتجدها مفيدة وملهمة.

‎إضافة تعليق