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hop_index2

Hop along multiple inputs simultaneously relative to an index

Description

hop_index2() and phop_index() represent the combination of slide2() and pslide() with hop_index(), allowing you to iterate over multiple vectors at once, relative to an .i-ndex with boundaries defined by .starts and .stops.

Usage

hop_index2(.x, .y, .i, .starts, .stops, .f, ...)

hop_index2_vec(.x, .y, .i, .starts, .stops, .f, ..., .ptype = NULL)

phop_index(.l, .i, .starts, .stops, .f, ...)

phop_index_vec(.l, .i, .starts, .stops, .f, ..., .ptype = NULL)

Arguments

`.x, .y`	`[vector]` Vectors to iterate over. Vectors of size 1 will be recycled.
`.i`	`[vector]` The index vector that determines the window sizes. It is fairly common to supply a date vector as the index, but not required. There are 3 restrictions on the index: The size of the index must match the size of `.x`, they will not be recycled to their common size. The index must be an increasing vector, but duplicate values are allowed. The index cannot have missing values.
`.starts, .stops`	`[vector]` Vectors of boundary values that make up the windows to bucket `.i` with. Both `.starts` and `.stops` will be recycled to their common size, and that common size will be the size of the result. Both vectors should be the same type as `.i`. These boundaries are both inclusive, meaning that the slice of `.x` that will be used in each call to `.f` is where `.i >= start & .i <= stop` returns `TRUE`.
`.f`	`[function / formula]` If a function, it is used as is. If a formula, e.g. `~ .x + 2`, it is converted to a function. There are three ways to refer to the arguments: For a single argument function, use `.` For a two argument function, use `.x` and `.y` For more arguments, use `..1`, `..2`, `..3` etc This syntax allows you to create very compact anonymous functions.
`...`	Additional arguments passed on to the mapped function.
`.ptype`	`[vector(0) / NULL]` A prototype corresponding to the type of the output. If `NULL`, the default, the output type is determined by computing the common type across the results of the calls to `.f`. If supplied, the result of each call to `.f` will be cast to that type, and the final output will have that type. If `getOption("vctrs.no_guessing")` is `TRUE`, the `.ptype` must be supplied. This is a way to make production code demand fixed types.
`.l`	`[list]` A list of vectors. The length of `.l` determines the number of arguments that `.f` will be called with. If `.l` has names, they will be used as named arguments to `.f`. Elements of `.l` with size 1 will be recycled.

Value

A vector fulfilling the following invariants:

`hop_index2()`

vec_size(hop_index2(.x, .y, .starts, .stops)) == vec_size_common(.starts, .stops)
vec_ptype(hop_index2(.x, .y, .starts, .stops)) == list()

`hop_index2_vec()`

vec_size(hop_index2_vec(.x, .y, .starts, .stops)) == vec_size_common(.starts, .stops)
vec_size(hop_index2_vec(.x, .y, .starts, .stops)[[1]]) == 1L
vec_ptype(hop_index2_vec(.x, .y, .starts, .stops, .ptype = ptype)) == ptype

`phop_index()`

vec_size(phop_index(.l, .starts, .stops)) == vec_size_common(.starts, .stops)
vec_ptype(phop_index(.l, .starts, .stops)) == list()

`phop_index_vec()`

vec_size(phop_index_vec(.l, .starts, .stops)) == vec_size_common(.starts, .stops)
vec_size(phop_index_vec(.l, .starts, .stops)[[1]]) == 1L
vec_ptype(phop_index_vec(.l, .starts, .stops, .ptype = ptype)) == ptype

Examples

# Notice that `i` is an irregular index!
x <- 1:5
i <- as.Date("2019-08-15") + c(0:1, 4, 6, 7)

# Manually create starts/stops. They don't have to be equally spaced,
# and they don't have to be the same size as `.x` or `.i`.
starts <- as.Date(c("2019-08-15", "2019-08-18"))
stops <- as.Date(c("2019-08-16", "2019-08-23"))

# The output size is equal to the common size of `.starts` and `.stops`
hop_index2(x, i, i, starts, stops, ~data.frame(x = .x, y = .y))

slider

Sliding Window Functions

v0.2.1

MIT + file LICENSE

Authors

Davis Vaughan [aut, cre], RStudio [cph]

Initial release