rts (version 1.1-14)

Extract by index: Exrtract values from raster time series

Description

This is a short-hand method that acts the same as extract. This method extracts values from a Raster*TS object for spatial locations which can be specified by spatial points, lines, polygons, or an Extent (rectangle) object or raster cell number(s).

Value

rts.

Methods

x[i, j]

Arguments

x is a raster time series (Raster*TS) object created by rts i is a SpatialPoints*, SpatialPolygons*, SpatialLines, Extent object, or a vector (representing cell numbers) j is optional; the time index for which the values in raster should be extracted. It can be numeric, timeBased or ISO-8601 style (see details)

Author

Babak Naimi

https://r-gis.net/

Details

This function uses the raster and xts packages to extract the values in space and subset them in time by specifying ISO-8601 compatible range strings. This allows for natural range-based time queries without requiring prior knowledge of the underlying time object used in construction.

When a raw character vector is used for j, it is processed as if it was ISO-8601 compliant. This means that it is parsed from left to right, according to the following specification:

CCYYMMDD HH:MM:SS.ss+

A full description will be expanded from a left-specified truncated one.

Additionally, one may specify range-based queries by simply supplying two time descriptions seperated by a forward slash:

CCYYMMDD HH:MM:SS.ss+/CCYYMMDD HH:MM:SS.ss

The algorithm to parse the above is .parseISO8601 from the xts package.

See Also

extract and [.xts

Examples

if (FALSE) {
file <- system.file("external/ndvi", package="rts")

ndvi <- rts(file) # read the ndvi time series from the specified file

n1 <- ndvi[125] # extract the time series values at cell number 125 for all available times

n1

plot(n1)

n2 <- ndvi[125,"/20090101"] # extract the time series values at cell number 125 for 
# all times after 2009-01-01

n2

plot(n2)

n3 <- ndvi[125,"200901/"] # extract the time series values at cell number 125 for all
# times before 2009-01

n4 <- ndvi[10:20,"2008-05-01"] #extract the values at cell numbers of 10:20 for 
# the specified time

n4


}