R: Class "STIDF"

STIDF-class {spacetime} | R Documentation

## Class "STIDF"

### Description

A class for unstructured spatio-temporal data; for n spatial locations and times, n observations are available

### Usage

      STI(sp, time, endTime)
      STIDF(sp, time, data, endTime)
      ## S4 method for signature 'STIDF'
    x[i, j, ..., drop = FALSE]
      ## S4 method for signature 'STIDF,STSDF'
    coerce(from, to, strict=TRUE)

### Arguments

`sp` | object of class Spatial
`time` | object holding time information; when STIDF is called, a non-ordered vector with times, e.g. POSIXct will also work, and rearrange the `sp` and `data` slots according to the ordering of time; for this to work no ties should exist.
`endTime` | vector of class `POSIXct`, indicating the end points of time intervals for the observations. By default, for `STI` objects `time` is taken, indicating that time intervals have zero width (time instances)
`data` | data frame with appropriate number of rows
`x` | an object of class STFDF
`i` | selection of record index (spatial/temporal/spatio-temporal entities)
`j` | or character string with temporal selection
`...` | first element is taken as column (variable) selector
`drop` | if TRUE and a single spatial entity is selected, an object of class xts is returned (NOT yet implemented); if TRUE and a single temporal entity is selected, and object of the appropriate `Spatial` class is returned; if FALSE, no coercion to reduced classes takes place
`from` | object of class STFDF
`to` | target class
`strict` | ignored

### Objects from the Class

Objects of this class carry full space/time grid data

### Slots

`sp`:

  Object of class `"Spatial"`

`time`:

  Object holding time information, see ST-class

`data`:

  Object of class `data.frame`, which holds the measured values

### Methods

[

  `signature(x = "STIDF")`: selects spatial-temporal entities, and attributes

### Note

arguments `sp`, `time` and `data` need to have the same number of records, and regardless of the class of time (xts or POSIXct) have to be in correspoinding order: the triple `sp[i]`, `time[i]` and `data[i,]` refer to the same observation

### Author(s)

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

### References

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

### Examples

    sp = cbind(x = c(0,0,1), y = c(0,1,1))
    row.names(sp) = paste("point", 1:nrow(sp), sep="")
    library(sp)
    sp = SpatialPoints(sp)
    time = as.POSIXct("2010-08-05")+3600*(10:13)
    m = c(10,20,30) # means for each of the 3 point locations
    mydata = rnorm(length(sp)*length(time),mean=rep(m, 4))
    IDs = paste("ID",1:length(mydata))
    mydata = data.frame(values = signif(mydata,3), ID=IDs)
    stidf = as(STFDF(sp, time, mydata), "STIDF")
    stidf[1:2,]
    all.equal(stidf, stidf[stidf,])

[Package spacetime version 1.2-2 Index]