| coffee | Coffee Data Set |
| emergency | Emergency Calls for Montgomery County, PA |
| fill_by_function | Fill missing values by a function of the nonmissings. |
| fill_by_prevalent | Fill missing values by the most prevalent nonnmissing value. |
| fill_by_value | Fill missing values by a single value. |
| get_interval | Get the interval of a datetime variable. |
| pad | Pad the datetime column of a data frame. |
| thicken | Add a variable of a higher interval to a data frame. |