over: Spatio-temporal overlay of 'Track' objects with 'Spatial' or...

In roland-h/trajaggr: Meaningful Aggregation of Trajectory Data in R

Description

Spatio-temporal overlay of Track objects with objects inheriting from class Spatial or STF objects as well as their data.frame counterparts.

For the spatial or spatio-temporal geometries of x the indices or attributes from the Track object are returned. If x inherts from class Spatial the returned object is extended, such that it respects the temporal information of the Track object. In particular that means that the returned object has one value (may also be NA) for each combination from the spatial geometries with the timestamps from the Track object.

If fn and weight.points are adequately specified a weighted aggregation is performed.

For further details please see the vignette!

Usage

## S4 method for signature 'STF,Track'
over(x, y, returnList = FALSE, fn = NULL, ...,
  use.data = FALSE, weight.points = NULL)

## S4 method for signature 'SpatialPolygons,Track'
over(x, y, returnList = FALSE,
  fn = NULL, ..., use.data = FALSE, weight.points = NULL)

## S4 method for signature 'SpatialPixels,Track'
over(x, y, returnList = FALSE,
  fn = NULL, ..., use.data = FALSE, weight.points = NULL)

## S4 method for signature 'SpatialGrid,Track'
over(x, y, returnList = FALSE, fn = NULL,
  ..., use.data = FALSE, weight.points = NULL)

Arguments

x	object of class Spatial or STF (see section 'Usage')
y	Track object
returnList	logical, indicates if a list should be returned
fn	(optional) aggregation function, that expects a vector of weights as its second argument if the argument weight.points is specified to perform a weighted aggregation.
...	optional additional arguments to fn
use.data	logical or a vevtor of indices or a vector of column names, indicating if indices (use.data = FALSE) or (optional aggregated) attribute values should be returned
weight.points	NULL, "byTime", "byDist" or "equal", indicating the basis of the weights that should be used for a weighted aggregation of attribute values

Value

The returned object depends on the specified arguments and it is consistent with the over methods defined in the packages sp and spacetime. For further details please see also the vignette.

Note

The weight.points argument should just be specified if a function that expects a vector of weights as its second argument is passed to fn.

Examples

## Load example toy data
load(system.file("extdata","trajaggr_TestData.RData", package = "trajaggr"), verbose = FALSE)
## Example 1: overlay of Track and Spatial object
# returnList = FALSE returns index vector
over_sp <- over(spPolys, Track_A1, returnList = FALSE)
dim(spPolys)
dim(Track_A1)
over_sp
# returnList = TRUE returns list of indices
over_sp <- over(spPolys, Track_A1, returnList = TRUE)
over_sp[1:7]
# use.data = TRUE and returnList = TRUE returns list of data.frames
over_sp <- over(spPolys, Track_A1, returnList = TRUE, use.data = TRUE)
over_sp[1:7]
# use.data = TRUE and returnList = FALSE returns data.frames 
# with (first) data element
over_sp <- over(spPolys, Track_A1, returnList = FALSE, use.data = TRUE)
over_sp[1:7, ]
##
## Example 2: overlay of Track and STF object with two time intervals
# returnList = FALSE returns index vector
over_stf <- over(stf_Polys_2t, Track_A1, returnList = FALSE)
dim(stf_Polys_2t)
dim(Track_A1)
over_stf
# returnList = TRUE returns list of indices
over_stf <- over(stf_Polys_2t, Track_A1, returnList = TRUE)
over_stf
# use.data = TRUE and returnList = TRUE returns list of data.frames
over_stf <- over(stf_Polys_2t, Track_A1, returnList = TRUE, use.data = TRUE)
over_stf
# use.data = TRUE and returnList = FALSE returns data.frames with (first) 
# data element
over_stf <- over(stf_Polys_2t, Track_A1, returnList = FALSE, use.data = TRUE)
over_stf
# use.data = TRUE and returnList = FALSE and fn = mean returns aggregated values
over_stf_mean <- over(stf_Polys_2t, Track_A1, returnList = FALSE, fn = mean, 
use.data = TRUE)
over_stf_mean
# use.data = TRUE and returnList = FALSE and fn = weighted.mean 
# and additionally specified weight.points = 'byTime' returns weighted 
# aggregated values
over_stf_wmean <- over(stf_Polys_2t, Track_A1, returnList = FALSE, 
fn = weighted.mean, weight.points = "byTime", use.data = TRUE)
over_stf_wmean

roland-h/trajaggr documentation built on Jan. 19, 2021, 1:02 p.m.