Rating is available when the video has been rented.
This feature is not available right now. Please try again later.
Published on Jul 1, 2013
When data are organized in a matrix or data frame, the apply() function can be used to calculate summaries (or apply a more complex function) across either the rows or columns of the data object. Or if summaries for each group (level) of one or more variables are desired, use the tapply() or by() function.