Stibu questions

Stibu answers

• R how to calculate 'Percentage of Change' between two rows?
• Calculations with minutes and seconds in R
• In R, how does group_by in dplyr work?
• ggplot to display same colors for factor levels [duplicate]
• how insert zeros in seq in R
• Pad (expand) only the top of continuous scale in ggplot2 [duplicate]
• Convert from billion to million and vice versa
• Aggregate data.frame for each day
• Overlay density plot excludes histogram values
• Why does the function t return a t.test for objects with class set to "test"?