The document provides an overview of single mode data structures in R, detailing types like numeric, integer, complex, logical, and character. It explains the creation and attributes of vectors, matrices, and arrays, including subscripting and referencing techniques. Key functions such as mode(), matrix(), and array() are also highlighted, emphasizing how matrices and arrays can be viewed as multi-dimensional vectors.

1. R
SINGLE MODE
DATA STRUCTURES
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2. INTRODUCTION
• Standard modes/types of data in R
• Numeric
• Double e.g. 2.3, 2.3e3, 2.3E3, 2.3E-2,
• Integer e.g. 23, -23
• Complex e.g. 2.3+3.2E2i
• Logical e.g. TRUE, FALSE, T, F
• Character e.g. “Hello”, ‘Hello’
• mode(): returns the mode of an object
• mode<-: sets the mode of an object is conversion function is available
• Single Mode Containers / Data Structures
• Vectors
• Matrices
• Arrays

3. VECTORS
• Definition
• Container for storing a series of values of same mode
• Fundamental data element - R scalars are vectors of length 1
• Creation
• Combine function
• Sequence operator x:y
• Sequence function
• seq(x, y, s)
• x, y, s can be double or integer (positive / negative)
• Repeat function
• rep(x, n)

4. VECTORS
• Attributes
• Length
• Names
• Mode

5. VECTORS
• Subscripting or Referencing
• VECTOR[index specification]
• VECTOR[index specification] <- value
• Specification
• Blank [] : all elements
• Positive integers: keep those elements
• Negative integers: drop those elements return rest
• Logical: keep only those which are TRUE in position
• Character: keep whose names are specified
• LETTERS and letters:
• In built vectors for uppercase and lowercase English alphabets

6. MATRICES
• Definition
• Container for storing a 2D (rows x columns) values of same mode
• Creation
• Combine series of vectors column or row wise with recycling
• Using matrix function
• Fills column wise
• By Row
• Attributes
• Mode
• Length – all elements
• Number of rows
• Number of columns
• Dimensions
• Dimension Names

7. MATRICES
• Subscripting or Referencing
• MATRIX[row index, col index]
• MATRIX[row index, col index] <- value
• Specification
• Blank [] : all elements
• Positive integers: keep those elements
• Negative integers: drop those elements return rest
• Logical: keep only those which are TRUE in position
• Character: keep whose names are specified
• Preserving Dimensions of matrix subset
• When one row or one column is returned the dimensions are dropped and a vector is returned
• To preserve dimensions use drop = FALSE option

8. MATRICES
• Logical Subscripting or Referencing
• Using dimension names
• Subscripting using row index only
• Returns a vector
• Subscripting as if the matrix is a vector

9. ARRAYS
• Definition
• Container for storing values of same mode any number of dimensions
• Creation
• Array function with dimensions
• Attributes
• Mode
• Length – all elements
• Dimensions
• Dimension Names

10. ARRAYS
• Subscripting or Referencing
• ARRAY[dim1 index, dim2 index, dim3 index…]
• ARRAY[dim1 index, dim2 index, dim3 index…] <- value
• Specification
• Blank [] : all elements
• Positive integers: keep those elements
• Negative integers: drop those elements return rest
• Logical: keep only those which are TRUE in position
• Character: keep whose names are specified
• Preserving Dimensions of array subset
• When one row or one column is returned the dimensions are dropped and a vector or matrix is
returned
• To preserve dimensions use drop = FALSE option

11. END NOTES
• Matrices and arrays are essentially vectors with dimensions
• Thus they can be morphed into one another