Can be used to create or modify attribute variables; for transforming
geometries see st_transform, and all other functions starting with
st_.
Usage
# S3 method for sftime
transform(`_data`, ...)Arguments
- _data
An object of class
sftime.- ...
Further arguments of the form new_variable=expression
Examples
# create 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)))
x <-
data.frame(a = 1:5, g, time = Sys.time() + 1:5, stringsAsFactors = FALSE)
x_sftime <- st_as_sftime(x)
x_sftime
#> Spatiotemporal feature collection with 5 features and 1 field
#> Geometry type: POINT
#> Dimension: XY
#> Bounding box: xmin: 1 ymin: 1 xmax: 3 ymax: 3
#> CRS: NA
#> Time column with classes: 'POSIXct', 'POSIXt'.
#> Ranging from 2023-09-01 10:23:38.862834 to 2023-09-01 10:23:42.862834.
#> a time geometry
#> 1 1 2023-09-01 10:23:38 POINT (1 2)
#> 2 2 2023-09-01 10:23:39 POINT (1 3)
#> 3 3 2023-09-01 10:23:40 POINT (2 3)
#> 4 4 2023-09-01 10:23:41 POINT (2 1)
#> 5 5 2023-09-01 10:23:42 POINT (3 1)
# modify values in column a
transform(x_sftime, a = rev(a))
#> Spatiotemporal feature collection with 5 features and 1 field
#> Geometry type: POINT
#> Dimension: XY
#> Bounding box: xmin: 1 ymin: 1 xmax: 3 ymax: 3
#> CRS: NA
#> Time column with classes: 'POSIXct', 'POSIXt'.
#> Ranging from 2023-09-01 10:23:38.862834 to 2023-09-01 10:23:42.862834.
#> a time geometry
#> 1 5 2023-09-01 10:23:38 POINT (1 2)
#> 2 4 2023-09-01 10:23:39 POINT (1 3)
#> 3 3 2023-09-01 10:23:40 POINT (2 3)
#> 4 2 2023-09-01 10:23:41 POINT (2 1)
#> 5 1 2023-09-01 10:23:42 POINT (3 1)