# as.quarterly: Aggregate Time Series In tframePlus: Time Frame Coding Kernel Extensions

## Description

Convert series to quarterly or annual.

## Usage

 ```1 2 3``` ``` as.quarterly(x, FUN=sum, na.rm=FALSE, ...) as.annually(x, FUN=sum, na.rm=FALSE, ...) as.weekly(x, FUN=sum, na.rm=FALSE, foldFrom=end(x), periodicity = 7) ```

## Arguments

 `x` a tframed object. (Only montly is currently working) `FUN` the function to use for aggregating. `na.rm` Logical indicating if `NA` should be removed from the beginning and end of a series `foldFrom` a date which is used to determine the end of weeks. `periodicity` the number of periods in a week. `...` additional arguments passed to `aggregate`

## Details

Functions `as.quarterly` and `as.annually` uses aggregate, but shifts the data to match usual economic and financial quarters or years (whereas aggregate simply groups together a number of periods corresponding to the new frequency starting with the first observation). These functions should give the same result as aggregate if the data starts and ends on quarter (annual) boundaries. If the data does not start and end on quarter (annual) boundaries then `NA` will be put in where data is incomplete, and the quarter (year) removed if `na.rm=TRUE`.

Monthly to annual gives the aggregate by converting first to quarterly, which is not exactly correct.

To weekly by `periodicity` groupings from `foldFrom`. Partial weeks in the beginning or end are padded with `NA` and dropped if `na.rm=FALSE`. (as.weekly has been tested only with daily 7 day weeks.)

## Value

time series

`tfwindow` `aggregate`
 ```1 2 3 4 5 6 7 8 9``` ``` z <- ts(1:10, start = c(1999,2), frequency=4) as.annually(z) as.annually(z, na.rm=TRUE) z <- ts(1:30, start = c(1999,2), frequency=12) as.annually(z) as.annually(z, na.rm=TRUE) as.quarterly(z) as.quarterly(z, na.rm=TRUE) ```