R courses

Higher-Dimensional Arrays Creating Higher-Dimensional Arrays Higher-dimensional arrays in R can be created using the array() function, which allows you to specify the dimensions and optionally names for each dimension. Example 1: Creating a 3D Array  # Creating a 3D array with dimensions 2x3x4 arr <- array(1:24, dim = c(2, 3, 4),              dimnames = list(c(“Layer1”,

Naming Rows and Columns of Matrices Creating a Matrix with Row and Column Names When you create a matrix, you can specify row and column names directly using the dimnames argument. Example 1: Creating with Names  # Creating a 2×3 matrix with row and column names m <- matrix(1:6, nrow = 2, byrow = TRUE,

Avoiding Unintended Dimension Reduction Context and Common Issues Unintended dimension reduction occurs when operations on matrices or vectors lead to an unexpected loss of dimensions. This often happens when performing selections, functions, or operations that modify the structure of data. Common Issues Subsetting: Selecting elements from a matrix might reduce it to a vector. Functions:

Changing the Size of a Matrix Expanding a Matrix Expanding a matrix means increasing its size by adding rows or columns. You can do this by creating a new matrix with the desired dimensions and then filling it with the original matrix’s data or new values. Example 1: Expanding a Matrix by Adding Rows and

Adding and Deleting Rows and Columns in a Matrix Adding Rows To add rows to a matrix, you use the rbind() function (row-bind), which stacks matrices or vectors by rows. Example 1: Adding a Row to a Matrix Suppose you have a matrix and want to add a new row:  # Example 1: Adding a

Applying Functions to Matrix Rows and Columns Using the apply() Function The apply() function is used to apply a function to the margins of a matrix. This is a very flexible and commonly used method for operations on rows or columns. Syntax of apply()  apply(X, MARGIN, FUN, …) X is the matrix. MARGIN is an

Filtering Matrices in R Filtering with Logical Conditions You can filter matrices using logical conditions. Logical conditions return a logical matrix where each element is TRUE or FALSE based on the specified condition. Example of Filtering with a Logical Condition Suppose you have a matrix and want to extract elements greater than a certain value: 

Matrix Indexing in R Basic Indexing Matrix indexing in R is done using the [row, column] notation. Here are some basic examples: Accessing a Single Element To access a single element, specify its row and column indices:  # Example 1: Accessing a single element m <- matrix(1:9, nrow = 3) # Access element in 2nd