R: Transition between data.frames containing sfc columns

tween_sf {transformr} | R Documentation

## Transition between data.frames containing sfc columns

### Description

This function is equivalent to `tweenr::tween_state()` except that it understands `sf::sfc` columns, as defined by the `sf` package. An `sfc` column is a column containing simple features and can this hold both points, lines polygons and more. `tween_sf` currently has support for (multi)point, (multi)linestring, and (multi)polygon types and requires that the transition is between compatible types (points-to-points, linestring-to-linestring, polygon-to-polygon). For (multi)linestring and (multi)polygon, the behavior is similar to `tween_path()` and `tween_polygon()` respectively, with each feature beeing run through the respective function with `match = FALSE`. For (multi)points it behaves more or less like `tweenr::tween_state()` except additional points are added as needed to make the to stages contain the same number of points. Points are added on top of existing points so it appears as if the points are divided into more.

### Usage

    tween_sf(.data, to, ease, nframes, id = NULL, enter = NULL, exit = NULL)

### Arguments

`.data` | A data.frame to start from. If `.data` is the result of a prior tween, only the last frame will be used for the tween. The new tween will then be added to the prior tween
`to` | A data.frame to end at. It must contain the same columns as .data (exluding `.frame`)
`ease` | The easing function to use. Either a single string or one for each column in the data set.
`nframes` | The number of frames to calculate for the tween
`id` | The column to match observations on. If `NULL` observations will be matched by position. See the Match, Enter, and Exit section for more information.
`enter` | functions that calculate a start state for new observations that appear in `to` or an end state for observations that are not present in `to`. If `NULL` the new/old observations will not be part of the tween. The function gets a data.frame with either the start state of the exiting observations, or the end state of the entering observations and must return a modified version of that data.frame. See the Match, Enter, and Exit section for more information.
`exit` | functions that calculate a start state for new observations that appear in `to` or an end state for observations that are not present in `to`. If `NULL` the new/old observations will not be part of the tween. The function gets a data.frame with either the start state of the exiting observations, or the end state of the entering observations and must return a modified version of that data.frame. See the Match, Enter, and Exit section for more information.

### Value

A data.frame containing intermediary states

### Examples

    library(magrittr)
    star_hole <- poly_star_hole(st = TRUE)
    circles <- poly_circles(st = TRUE)
    spiral <- path_spiral(st = TRUE)
    waves <- path_waves(st = TRUE)
    random <- point_random(st = TRUE)
    grid <- point_grid(st = TRUE)
    df1 <- data.frame(geo = sf::st_sfc(star_hole, spiral, random))
    df2 <- data.frame(geo = sf::st_sfc(circles, waves, grid))

    tween_sf(df1, df2, 'linear', 30)

[Package transformr version 0.1.3 Index]