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Questions and Answers
What is R primarily used for?
What is R primarily used for?
R is primarily used for statistical computing and graphical presentation.
Who created the R programming language?
Who created the R programming language?
R was created by Ross Ihaka and Robert Gentleman.
What are variables in R used for?
What are variables in R used for?
Variables in R are reserved memory locations used to store values.
How does R handle data types for variables?
How does R handle data types for variables?
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List the five atomic vectors in R.
List the five atomic vectors in R.
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What is a vector in R?
What is a vector in R?
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What kind of operations can be applied to variables based on their data type?
What kind of operations can be applied to variables based on their data type?
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Why is R considered effective for data analysis?
Why is R considered effective for data analysis?
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Study Notes
Unit 1: Data Preprocessing
- This unit focuses on data preprocessing for use in analysis.
Quick Revision of R
- R is a programming language for statistical computing and graphical presentation.
- Its primary use is to analyze and visualize data.
- Developed by Ross Ihaka and Robert Gentleman at the University of Auckland, New Zealand.
- R is a programming language and software environment.
Features of R
- Well-developed, simple, and effective programming language.
- Includes conditionals, loops, user-defined recursive functions, and input/output facilities.
- Effective data handling and storage.
- Provides operators for calculations on arrays, lists, vectors, and matrices.
- Contains a large integrated collection of tools for data analysis.
- Offers graphical facilities for data analysis and display.
Variables
- Variables are reserved memory locations to store data values.
- Creating a variable reserves space in memory.
Data Types
- Data types classify variable values and the appropriate mathematical, relational, or logical operations that can be applied without error.
R Objects
- R variables are not explicitly declared with data types. Instead, they are assigned R objects, and the resulting R object's type becomes the variable's type.
- Common R objects include: Vectors, Lists, Matrices, Arrays, Factors, and Data Frames.
Briefing of Data Types
-
A vector is a sequence of data elements of the same data type.
-
Five atomic vector types/classes:
- Logical (TRUE/FALSE)
- Integer (e.g., 15L, 30L)
- Numeric (e.g., 5, 3.14, 9452)
- Complex (e.g., 4+3i)
- Character (e.g., "A", "Hey")
-
Example using vectors:
-
subject_name <- c("John Doe", "Jane Doe", "Steve Graves") -
temperature <- c(98.1, 98.6, 101.4) -
flu_status <- c(FALSE, FALSE, TRUE)
-
Factors
- Factors are data objects used to categorize and store data as levels.
- Created using the
factor()function with a vector. - Useful for repeated values.
- Example:
data <- c("East", "West","East","North","North","East","West","West","West","East","North") factor_data <- factor(data)
- Example:
Lists
- Lists are R objects that can contain elements of different data types (numbers, strings, vectors, or other lists).
- Created using the
list()function.- Example:
list_data <- list("Red", "Green", c(21,32,11), TRUE, 51.23, 119.1) print(list_data)
- Example:
Data Frame
- A data frame is a two-dimensional table structure.
- Columns contain values of a single variable.
- Rows contain a collection of values, one from each column.
- Characteristics include:
- Column names must be non-empty
- Row names must be unique
- Data can be numeric, factor, or character
- Each column must have the same number of data items as other columns.
- Example:
dataframe <- data.frame(name = c("John", "Mary", "Hyka"), age = c(20, 21, 22), course = c("cse", "ece","eee"), stringsAsFactors = "FALSE") dataframe
Matrices
- Matrices are R objects where elements are arranged in a two-dimensional rectangular layout.
- Contain elements of the same atomic type (e.g., numeric)
- Used in mathematical calculations.
- Created using the
matrix()function. - Syntax:
matrix(data, nrow, ncol, byrow, dimnames)-
data: Input vector for matrix elements -
nrow: Number of rows -
ncol: Number of columns -
byrow: TRUE for row-wise filling of elements. -
dimnames: Names for rows and columns (optional).
-
Arrays
- Arrays are R objects that can store data in more than two dimensions.
- Created using the
array()function, which takes vectors and thedimparameter (defining dimensions) as input.
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Description
This quiz covers the essentials of data preprocessing and the R programming language. It focuses on the features of R, how to create variables, and the classification of data types, providing a foundational understanding for data analysis. Test your knowledge of these crucial concepts.
