In R, we create a vector of numbers using the c() function, and then calculate the mean and median using the mean() and median() functions. For example, x <- c(1, 2, 3, 4, 5); mean(x); median(x) would create a vector and compute the mean and median of its elements.

In R, the t.test() function can be used to conduct a t-test. The t.test() function is used for hypothesis testing with continuous variables, comparing means between two groups and determining if the difference is statistically significant.

Factors are the data objects which are used to categorize the data and store it as levels. They can store both strings and integers. They are useful in data analysis for statistical modeling.

Some functions in R that operate specifically on matrices include dim() for retrieving the dimensions of a matrix, rowSums() and colSums() for calculating the row and column sums, rowMeans() and colMeans() for calculating the row and column means, and t() for transposing a matrix. These functions provide convenient ways to perform operations and calculations on matrices.

The arrows() function in R can be used to add error bars to a bar chart. By specifying the coordinates and lengths of the error bars, the function will draw lines with arrows representing the error or uncertainty associated with each bar.

When working with large data sets in R and aiming to create a plot that clearly communicates key findings, it is important to simplify the plot by focusing on the most important variables or relationships. Select appropriate plot types that highlight the desired insights, provide clear and concise annotations or labels to enhance understanding, and consider using interactive elements or drill-down capabilities to explore details. The combination of these approaches will help create an effective plot that effectively communicates the key findings.

In R, a list is a versatile data structure that can store multiple values of different data types. Unlike vectors, which can only contain elements of the same data type, lists in R can hold elements of any type, including vectors, matrices, other lists, and even functions. Lists provide flexibility in organizing and storing heterogeneous data.

In R, the escape character is used to represent a backslash. For example, "C:Documentsfile.txt" represents the file path "C:Documentsfile.txt".

In R, a matrix is created using the matrix() function. The matrix() function allows you to specify the values of the matrix, the number of rows and columns, and other parameters such as column names and row names.

All of the mentioned options, including bar charts, stacked bar charts, and treemaps, are alternatives to pie charts for visualizing proportions in a dataset in R. These alternative visualizations offer different ways to represent proportions and can be more effective in certain situations.