mapmaxyear: Maximum NDVI value of a given year
In ndvits: NDVI Time series extraction and analysis

Description Usage Arguments Details Value Author(s) See Also Examples

Compute for each pixel, the maximum NDVI value of the year.

1	mapmaxyear(ndvidirectory, region, year, xlim = NULL, ylim = NULL, outfile = FALSE, type="VITO_CLIP")

`ndvidirectory`	path to the ndvi images folder (GeoTIFF files). Please note that paths to files in R can be specified with either "/" or "\\" in Windows OS and with "/" in UNIX OS.
`region`	name of the region, same as in the name of the ndvi images. Please refer to details section for more information on the nomenclature.
`year`	year of the analysis (in four-digit format).
`xlim`	a two dimensions vector containing the longitude limits of the area of interest. `xlim`=NULL indicates no longitude limits. By default, `xlim`=NULL. Please note that `xlim` have to be in the same units and projection as the ndvi maps.
`ylim`	a two dimensions vector containing the latitude limits of the area of interest. `ylim`=NULL indicates no longitude limits. By default, `ylim`=NULL. Please note that `ylim` have to be in the same units and projection as the ndvi maps.
`outfile`	file where the map of the maximum is saved (extension=".tif"). If `outfile`=FALSE, the map is not saved. By default, `outfile` = FALSE.
`type`	type of nomenclature followed by the NDVI images : "VITO_CLIP", "VITO_VGT" or "GIMMS" (see details for more information). By default, `type` = "VITO_CLIP".

mapmaxyear load one maps after another and keep the maximum. It is less memory and time demanding than maplocalstat.

More about the variable type :
type = GIMMS : nomenclature from Global Land Cover Facility
[RE][YY][MMM][DDD].[SAT]-VIg.tif

RE : identifies the continent (AF for Africa,AZ for Australia and New Zealand, EA for Eurasia, NA for North America and SA for South America and Central America)
YY : the two last digits of the year
MMM : three-letter abbreviation of the month
DDD : identifies the composite period, 15a denotes the days 1-15 of the month, and 15b denotes the days from 16 to the end of the month.
SAT : identifies the satellite, NOAA-7, 9, 11, 14, 16, or 17 from which the data originated.

type = VITO_VGT : FreeVGT VITO's nomenclature
NDV_[YYYYMMDD]_[REGION]_Extract.tif

YYYY : identifies the year (four digits)
MM : identifies the months (two digits)
DD : identifies the date of the period : "01", "11" or "21" (10-day composite).
REGION : idendifies the region selected while extracting maps

type = VITO_CLIP : nomenclature after clipping the images in a particular region.
[REGION][YYYY]M[MM]P[D].tif

REGION : the region as entered while clipping data.
YYYY : identifies the year (four digits)
MM : identifies the months (two digits)
D : identifies the period (0, 1 or 2).

The function returns the map with the maximum of the year.

Romain Frelat and Bruno Gerard

maplocalstat

#local variables
ndvidirectory=paste(system.file("extdata/VITO_Mzimba",
    package="ndvits"), "/", sep="")
region="Mzimba"
year=2004

#processing the map of the maximum in 2004
max=mapmaxyear(ndvidirectory, region, year)

#display the map
savemap(max)