Apply several summary functions (sum, mean, etc.) on several variables by group in one call...

Converting year and month ("yyyy-mm" format) to a date?...

Add legend to ggplot2 line plot...

Plotting two variables as lines using ggplot2 on the same graph...

How to generate permutations or combinations of object in R?...

What does "The following object is masked from 'package:xxx'" mean?...

How to convert character of percent into numeric in R...

What is the difference between = and == in R?...

How to use a variable to specify column name in ggplot...

Transpose / reshape dataframe without "timevar" from long to wide format...

`lm` summary not display all factor levels...

Different legend-keys inside same legend in ggplot2...

How can I trim leading and trailing white space?...

Test if characters are in a string...

ending "+" prompt in R...

How do I get a list of built-in data sets in R?...

Subset / filter rows in a data frame based on a condition in a column...

Drop data frame columns by name...

Using ggplot2, can I insert a break in the axis?...

Side-by-side plots with ggplot2...

How to subtract years?...

How do I make a list of data frames?...

How to find all functions in an R package?...

Select rows from a data frame based on values in a vector...

Order of operator precedence when using ":" (the colon)...

Test if a vector contains a given element...

Evaluate expression given as a string...

Replace all 0 values to NA...

How to unload a package without restarting R...

How to plot a function curve in R...