st_as_sftime: Convert a foreign object to an 'sftime' object

In sftime: Classes and Methods for Simple Feature Objects that Have a Time Column

Convert a foreign object to an sftime object

Description

Convert a foreign object to an sftime object

Usage

st_as_sftime(x, ...)

## S3 method for class 'ST'
st_as_sftime(x, ...)

## S3 method for class 'Track'
st_as_sftime(x, ...)

## S3 method for class 'Tracks'
st_as_sftime(x, ...)

## S3 method for class 'TracksCollection'
st_as_sftime(x, ...)

## S3 method for class 'sftime'
st_as_sftime(x, ...)

## S3 method for class 'sf'
st_as_sftime(x, ..., time_column_name = NULL)

## S3 method for class 'stars'
st_as_sftime(x, ..., long = TRUE, time_column_name = NULL)

## S3 method for class 'data.frame'
st_as_sftime(
  x,
  ...,
  agr = NA_agr_,
  coords,
  wkt,
  dim = "XYZ",
  remove = TRUE,
  na.fail = TRUE,
  sf_column_name = NULL,
  time_column_name = NULL,
  time_column_last = FALSE
)

Arguments

x	An object to be converted into an object of class sftime.
...	Further arguments passed to methods.
time_column_name	A character value; name of the active time column. In case there is more than one and time_column_name is NULL, the first one is taken.
long	A logical value; See st_as_sf. Typically, long should be set to TRUE since time information typically is a dimension of a stars object.
agr	A character vector; see details section of st_sf.
coords	In case of point data: names or numbers of the numeric columns holding coordinates.
wkt	The name or number of the character column that holds WKT encoded geometries.
dim	Passed on to st_point (only when argument coords is given).
remove	A logical value; when coords or wkt is given, remove these columns from codedata.frame?
na.fail	A logical value; if TRUE, raise an error if coordinates contain missing values.
sf_column_name	A character value; name of the active list-column with simple feature geometries; in case there is more than one and sf_column_name is NULL, the first one is taken.
time_column_last	A logical value; if TRUE, the active time column is always put last, otherwise column order is left unmodified. If both sfc_last and time_column_last are TRUE, the active time column is put last.

Value

x converted to an sftime object.

st_as_sftime.Tracks furthermore adds a column track_name with the names of the tracks slot of the input Tracks object.

st_as_sftime.TracksCollection furthermore adds the columns tracks_name with the names of the tracksCollection slot and track_name with the names of the tracks slot of the input Tracks object.

Examples

# modified from spacetime:
library(sp)
library(spacetime)

sp <- cbind(x = c(0,0,1), y = c(0,1,1))
row.names(sp) <- paste("point", 1:nrow(sp), sep="")
sp <- SpatialPoints(sp)
time <- as.POSIXct("2010-08-05") + 3600 * (10:12)
x <- STI(sp, time)

st_as_sftime(x)

# convert a Track object from package trajectories to an sftime object
library(trajectories)
x1_Track <- trajectories::rTrack(n = 100)
x1_Track@data$speed <- sort(rnorm(length(x1_Track)))
x1_sftime <- st_as_sftime(x1_Track)

# convert a Tracks object from package trajectories to an sftime object
x2_Tracks <- trajectories::rTracks(m = 6)
x2_sftime <- st_as_sftime(x2_Tracks)

# convert a TracksCollection object from package trajectories to an sftime object
x3_TracksCollection <- trajectories::rTracksCollection(p = 2, m = 3, n = 50)
x3_sftime <- st_as_sftime(x3_TracksCollection)

# convert an sftime object to an sftime object
st_as_sftime(x3_sftime)
  
# convert an sf object to an sftime object
g <- st_sfc(st_point(c(1, 2)), st_point(c(1, 3)), st_point(c(2, 3)), 
     st_point(c(2, 1)), st_point(c(3, 1)))
x4_sf <- st_sf(a = 1:5, g, time = Sys.time() + 1:5)
x4_sftime <- st_as_sftime(x4_sf) 

# convert a Tracks object from package trajectories to an sftime object
x5_stars <- stars::read_stars(system.file("nc/bcsd_obs_1999.nc", package = "stars"))
x5_sftime <- st_as_sftime(x5_stars, time_column_name = "time")

# this requires some thought to not accidentally drop time dimensions. For
# example, setting `merge = TRUE` will drop the time dimension and thus throw
# an error:
## Not run: 
x5_sftime <- st_as_sftime(x5_stars, merge = TRUE, time_column_name = "time")

## End(Not run)

# convert a data frame to an sftime object
x5_df <- 
   data.frame(a = 1:5, g, time = Sys.time() + 1:5, stringsAsFactors = FALSE)
x5_sftime <- st_as_sftime(x5_df)

sftime documentation built on March 18, 2022, 7:11 p.m.