st_sftime: Construct an 'sftime' object from all its components

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

Construct an sftime object from all its components

Description

Construct an sftime object from all its components

Usage

st_sftime(
  ...,
  agr = sf::NA_agr_,
  row.names,
  stringsAsFactors = TRUE,
  crs,
  precision,
  sf_column_name = NULL,
  time_column_name = NULL,
  check_ring_dir = FALSE,
  sfc_last = TRUE,
  time_column_last = TRUE
)

## S3 method for class 'sftime'
x[i, j, ..., drop = FALSE, op = sf::st_intersects]

## S3 replacement method for class 'sftime'
x[[i]] <- value

## S3 replacement method for class 'sftime'
x$i <- value

Arguments

...	Column elements to be binded into an sftime object or a single list or data.frame with such columns. At least one of these columns shall be a geometry list-column of class sfc and one shall be a time column (to be specified with time_column_name).
agr	A character vector; see details below.
row.names	row.names for the created sf object.
stringsAsFactors	A logical value; see st_read.
crs	Coordinate reference system, something suitable as input to st_crs.
precision	A numeric value; see st_as_binary.
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_name	A character value; name of the active time column. In case time_column_name is NULL, the first POSIXct column is taken. If there is no POSIXct column, the first Date column is taken.
check_ring_dir	A logical value; see st_read.
sfc_last	A logical value; if TRUE, sfc columns are always put last, otherwise column order is left unmodified.
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.
x	An object of class sf.
i	Record selection, see [.data.frame
j	Variable selection, see [.data.frame
drop	A logical value, default FALSE; if TRUE drop the geometry column and return a data.frame, else make the geometry sticky and return an sf object.
op	A function; geometrical binary predicate function to apply when i is a simple feature object.
value	An object to insert into x.

Details

See also [.data.frame; for [.sftime ... arguments are passed to op.

Value

st_sftime: An object of class sftime.

Returned objects for subsetting functions: [.sf will return a data.frame or vector if the geometry column (of class sfc) is dropped (drop=TRUE), an sfc object if only the geometry column is selected, and otherwise return an sftime object.

Examples

## construction with an sfc object
library(sf)
g <- st_sfc(st_point(1:2))
tc <- Sys.time()
st_sftime(a = 3, g, time = tc)

## construction with an sf object
## Not run: 
st_sftime(st_sf(a = 3, g), time = tc) 
# error, because if ... contains a data.frame-like object, no other objects 
# may be passed through ... . Instead, add the time column before.

## End(Not run)

st_sftime(st_sf(a = 3, g, time = tc))

## Subsetting
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)))
tc <- Sys.time() + 1:5
x <- st_sftime(a = 1:5, g, time = tc)

# rows
x[1, ]
class(x[1, ])

x[x$a < 3, ]
class(x[x$a < 3, ])

# columns
x[, 1]
class(x[, 1]) # drops time column as for ordinary data.frame subsetting, 
# keeps geometry column of sf object

x[, 3]
class(x[, 3]) # keeps time column because it is explicitly selected,
# keeps geometry column of sf object, returns an sftime object

x[, 3, drop = TRUE] 
class(x[, 3, drop = TRUE]) # if the geometry column is dropped, not only the
# sf class is dropped, but also the sftime class

x["a"]
class(x["a"]) # Time columns are not sticky: If a column is selected by a 
# character vector and this does not contain the active time column, the time 
# column is dropped. 

x[c("a", "time")]
class(x[c("a", "time")]) # keeps the time column

# with sf or sftime object 
pol = st_sfc(st_polygon(list(cbind(c(0,2,2,0,0),c(0,0,2,2,0)))))
h = st_sf(r = 5, pol)

x[h, ] 
class(x[h, ]) # returns sftime object

h[x, ] 
class(h[x, ]) # returns sf object

## Assigning values to columns

# assigning new values to a non-time column
x[["a"]] <- 5:1
class(x)

# assigning allowed new values to the time column
x[["time"]] <- Sys.time() + 1:5
class(x)

# assigning new values to the time column which invalidate the time column
x[["time"]] <- list(letters[1:2])
class(x)

# assigning new values with `$`
x$time <- Sys.time() + 1:5
class(x)

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