slide_by_geo: Slide a function over values in 'covidcast_signal' data...

In dshemetov/modeltools-mirror: Tools for Building COVID Forecasters and Related Models

Description

Slides a given function over the values in a covidcast_signal data frame, grouped by geo_value. (When multiple issue dates are present, only the latest issue is considered.) See the getting started guide for examples.

Usage

slide_by_geo(
  x,
  slide_fun,
  n = 14,
  shift = 0,
  col_name = "slide_value",
  col_type = c("dbl", "int", "lgl", "chr", "list"),
  ...
)

Arguments

x	The covidcast_signal data frame under consideration.
slide_fun	Function or formula to slide over the values in x, grouped by geo_value. To "slide" means to apply the function or formula over a right-aligned window of n days of data. If a function, slide_fun must take x, a data frame the same column names as the original data frame; followed by any number of named additional arguments; and ending with ..., to capture general additional arguments. If a formula, slide_fun can operate directly on .x$value, .x$time_value, etc., as in ~ mean(.x$value) to compute a trailing mean over the last n days of data.
n	Size of the local window (in days) to use. Default is 14.
shift	Number of days forward from the time_value to shift the window. Because the window is right-aligned, if n = 5 and shift = 0, then for a time_value of November 5, the function will be applied to values from November 1 to November 5. A positive value shifts the window forwards in time, while negative values shift the window backwards in time. Ex: for a time_value of November 5 shift = 3 captures November 4 through November 8; shift = -3 captures October 29 through November 2. Default is not to shift.
col_name	String indicating the name of the new column that will contain the derivative values. Default is "slide_value"; note that setting col_name = "value" will overwrite the existing "value" column.
col_type	One of "dbl", "int", "lgl", "chr", or "list", indicating the data type (as tibble abbreviation) for the new column. Default is "dbl".
...	Additional arguments to pass to the function or formula specified via slide_fun.

Value

A data frame given by appending a new column to x named according to the col_name argument, containing the function values.

Examples

## Not run: 
df <- covidcast::covidcast_signal("fb-survey", "smoothed_cli", 
    start_day = "2021-01-01", 
    end_day = "2021-01-31",
    geo_type = "state")
    
# two equivalent ways to compute 7-day trailing averages
slide_by_geo(df, slide_fun = ~ Mean(.x$value), n = 7)
slide_by_geo(df, slide_fun = function(x, ...) Mean(x$value) , n = 7)

## End(Not run)

dshemetov/modeltools-mirror documentation built on Jan. 7, 2022, 12:23 a.m.