Dear readers, these R language interview questions are specially designed to help you deal with questions you may be asked in R language-related interviews. In my experience, a good interviewer is hardly going to ask any specific questions in your interview, and usually starts with the following questions to further develop the subsequent questions.
What is R language programming?
R is a programming language used for statistical analysis and to create graphs for this purpose. Not a data type, it has a data object for calculation. It is used in areas such as data mining, regression analysis, probability estimation, etc., using many software packages available in it.
What are the different data objects in R language?
They are 6 data objects in R language. They are vectors, lists, arrays, matrices, dataframes, and tables.
What makes valid variable names in R language?
Valid variable names consist of letters, numbers, and dots or underscore characters. Variable names begin with letters or do not follow numbers.
What are the main differences between arrays and matrices?
Matrix is always two-dimensional because it only has rows and columns. But the array can have any number of dimensions, and each dimension is a matrix. For example, a 3x3x2 array represents 2 matrices with dimensions of 3x3.
Which data object in R is used to store and process classified data?
Factor data objects in R language are used to store and process classified data in R language.
How to load and use csv files in R language?
You can use R language functions to load csv files. R language creates a data frame when reading a csv file using this function.
How to get the name of the current working directory in R language?
The command getwd() gives the current working directory in the R locale environment.
What is R language Base package?
This is the package that is loaded by default when setting the R locale. It provides basic functions in the R locale environment such as input/output, arithmetic calculations, etc.
How to use R language in logistic regression?
Logistic regression processes measure the probability of binary response variables. In R language, the function glm() is used to create logistic regression.
How to access elements in column 2 and row 4 of a matrix named M?
Expression M [4,2] gives the elements of row 4 and column 2.
What is the recycling of elements in vectors? Give an example.
When two vectors of different lengths are involved in an operation, the elements of the shorter vector are reused to complete the operation. This is called element loop. Examples -v1 <-c(4,1,0,6) and V2 <-c(2,4), then v1 * v2 gives (8,4,0,24). Repeat elements 2 and 4.
What are the different ways to call functions in R language?
We can call a function in R language in 3 ways. The first method is to call it by using the location of the parameter. The second method id is called by using the name of the parameter, and the third method is called by the default parameter.
What is delay function evaluation in R language?
Delay evaluation of a function means that parameters are evaluated only when it is used inside the function body. If there is no reference to the parameters in the function body, it is simply ignored.
How to install software packages in R language?
To install a package in R language, we use the following command.
（"package Name"）
Name the R language package used to read XML files.
A package named "XML" is used to read and process XML files.
Can we update and delete any elements in the list?
We can update any element, but we can only delete the elements at the end of the list.
Create a matrix for general expressions in R language.
The general expression for creating a matrix in R language is - matrix(data, nrow, ncol, byrow, dimnames)
This function is used to create boxplot graphs in R language?
The boxplot() function is used to create box plots in R language. It creates a box plot using formulas and data frames as inputs.
When doing time series analysis, what does the fR language equality = 6 mean in the ts() function?
Frequency 6 indicates that the time interval of time series data is one hour every 10 minutes.
What is data reshaping in R language?
In R language, data objects can be converted from one form to another. For example, we can create a data frame by merging many lists. This involves a series of R language commands to bring data into a new format. This is called data shaping.
What is the output of R language unif(4)?
It generates 4 random numbers between 0 and 1.
How to get a list of all packages installed in R language?
Use commands
()
What does running command - strsplit(x, "e") mean?
It splits the string in the vector x into a substring at the position of the letter e.
Give an R script to extract all unique words in capital from a string - "Fast brown fox jumps over lazy dog".
x<- “Fast brown fox jumps over lazy dog” <- strsplit(x，"") <- [[1]] result <- unique(tolower()) print(result)
The vector v is c (1,2,3,4), the list x is list (5:8), what is the output of v*x[1]?
Error in v * x [1]: Nonnumerical parameters of binary operators
The vector v is c (1,2,3,4), the list x is list (5:8), what is the output of v*x [[1]]?
[1] 5 12 21 32s
What is unlist()?
It converts the list into a vector.
Give R language expressions to get 26 or less heads from 51 coins using pbinom.
x <- pbinom(26,51,0.5) print(x) XYes vectorc(5,9.2,3,8.51，NA)，mean(x)What is the output？ NA
How to convert data in a JSON file into a data frame?
Use function()
Given a function in R language, replacing all missing values of vector x with the sum of elements of vector?
function(x){x [(x)] <sum(x, = TRUE); x }
What is the purpose of apply() in R language?
It is used to apply the same function to each element in the array. For example, find the average value of rows in each row.
Is an array called a matrix or a matrix called an array?
Each matrix can be called an array, but not the other way around. Matrixes are always two-dimensional, but arrays can be any dimension.
How to find the help page with missing values?
?NA
How to get the standard deviation of vector x?
sd(x, = TRUE)
How to set the path to the current working directory in R language?
setwd("Path")
What is the difference between "%%" and "%/%"?
"%%" gives the remainder of the division between the first vector and the second vector, while "%/%" gives the quotient of the division between the first vector and the second vector.
What is (x)?
Find the column has the maximum value for each row.
Gives the command to create a histogram.
hist()
How to delete vectors from R language workspace?
rm(x)
List the available datasets in the package "MASS"
data(package ="MASS")
Lists the available datasets in all available packages.
data(package = .packages( = TRUE))
What is the use of commands - ((),repos = NULL)?
It is used to install R language packages from local directories by browsing and selecting files.
A command is given to check whether element 15 exists in vector x.
15%exist%x
Given the syntax for creating a scatter plot matrix.
pairs(formula, data)
Where the formula represents the series of variables used in pairs, the data represents the data set from which the variables are obtained.
What is the difference between subset() function and sample() function in R language?
The subset() function is used to select variables and observe values. The sample() function is used to select a random sample of size n from the dataset.
How to check that "m" is a matrix data object in R language?
(m) TRUE should be re-run.
What is the output of the following expression all(NA == NA)?
[1] NA
How to get the transpose of a matrix in R language?
The function t() is used to transpose the matrix. Example -t(m), where m is a matrix.
What is the use of "next" statement in R language?
The "next" statement in the R programming language is useful when we want to skip the current iteration of the loop without terminating it.
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