Here's how you can solve the practice exercises:

Selecting Specific Dates in a Dataframe in R with lubridate Package

Subsetting the mtcars Dataset: A Step-by-Step Guide to Filtering and Calculating Mean Values

Reading Multiple Text Files into Separate Data Frames in R: A Better Approach

Exporting Custom Data from R to Excel with Openxlsx

Fixing the 'Unused Arguments' Error in Shiny Applications: A Step-by-Step Guide to Effective Reactive Value Usage

Deleting Columns and Rows from a Kinship Matrix in R Using dimnames and Subset Methods

How to Reorder Coefficients and Rename Predictor Names with stargazer Package in R

Understanding Barplots in R: Addressing Missing Labels and Customization Techniques

How to Save and Read a DuckDB Database in R: A Step-by-Step Guide