R: consistent spatio-temporal overlay for objects inheriting...

over-methods {spacetime} | R Documentation

## consistent spatio-temporal overlay for objects inheriting from ST

### Description

consistent spatio-temporal overlay for STF, STS and STI objects, as well as their *DF counterpart: retrieves the indexes or attributes from one geometry at the spatio-temporal points of another

### Usage

    ## S4 method for signature 'STF,STF'
    over(x, y, returnList = FALSE, fn = NULL, ...)
    ## S4 method for signature 'xts,xts'
    over(x, y, returnList = FALSE, fn = NULL, ...)
    ## S4 method for signature 'ST'
    aggregate(x, by, FUN, ..., simplify = TRUE)

### Arguments

`x` | geometry (S/T locations) of the queries
`y` | layer from which the geometries or attributes are queried
`returnList` | logical; determines whether a list is returned, or an index vector
`fn` | (optional) a function; see value
`by` | geometry over which attributes in `x` are aggregated (this can be a `Spatial*` geometry, or a `ST*` geometry), or temporal aggregation, such as "month", "10 minutes", or a function such as as.yearmon; see aggregate.zoo. In case `x` is of class STFDF, argument `by` may be "time" or "space", in which cases aggregation over all time or all space is carried out.
`FUN` | aggregation function
`simplify` | boolean; if TRUE, and space or time dimensions can be dropped, the simpler (`Spatial` or `xts`) object will be returned
`...` | arguments passed on to function fn or FUN

### Value

an object of length `length(x)`, or a data.frame with number of rows equal to `length(x)`. If `returnList` is FALSE, a vector with indices of `y` for each geometry (point, grid cell centre, polygon or lines x time point) in `x`. if `returnList` is TRUE, a list of length `length(x)`, with list element `i` the vector of indices of the geometries in `y` that correspond to the $i$-th geometry in `x`.

The `aggregate` method for `ST` objects aggregates the attribute values of `x` over the geometry (space, time, or space-time) of `by`, using aggregation function `FUN`.

For the matching of time intervals, see timeMatch.

For setting, or retrieving whether time represents intervals, see timeIsInterval.

### Methods

x = "STF", y = "STF"
x = "xts", y = "xts"

  finds the row index of the instance or interval of time instances of `x` matching to `y`. Only if `timeIsInterval(x) == TRUE`, intervals are sought. In that case, time intervals start at the time instance of a record, and end at the next. The last time interval length is set to the interval length of the one-but-last (non-zero) interval. In case of a single time instance for `y`, its interval is right-open.

### Note

See also over; methods intersecting SpatialLines with anything else, or SpatialPolygons with SpatialPolygons, need rgeos to be loaded first.

### Author(s)

Edzer Pebesma, edzer.pebesma@uni-muenster.de

### References

http://www.jstatsoft.org/v51/i07/

### See Also

over; `vignette('sto')`, `vignette('over')`, timeMatch, timeIsInterval

[Package spacetime version 1.2-2 Index]