xtractomatic (version 3.4.2)

xtractogon: Extract environmental data in a polygon using ERDDAP.

Description

xtractogon uses the ERD ERDDAP data web service to extact environmental data inside a polygon defined by vectors of latitudes and longitudes

Usage

xtractogon(dtype, xpos, ypos, tpos = NA, verbose = FALSE)

Arguments

dtype

- number or string identifying the ERDDAP parameter to extract

xpos

- array giving longitudes (in decimal degrees East, either 0-360 or -180 to 180) of polygon

ypos

- array giving latitudes (in decimal degrees N; -90 to 90)of polygon

tpos

- 2-element array giving min and max time (specify both minimum and maximum dates). For the last available time, use "last". Default NA.

verbose

- logical for verbose download out, default FALSE

Value

structure with data and dimensions

• extract$data - the masked data array dimensions (lon,lat,time)

• extract$varname - the name of the parameter extracted

• extract$datasetname - ERDDAP dataset name

• extract$longitude - the longitudes on some scale as request

• extract$latitude - the latitudes always going south to north

• extract$time - the times of the extracts

Details

xtractogon extracts the data from the smallest bounding box that contains the polygon, and then uses the function "point.in.polygon" from the "sp" package to mask out the areas outside of the polygon.

Examples

# NOT RUN {
tpos <- c("2014-09-01", "2014-10-01")
xpos <- mbnms$Longitude
ypos <- mbnms$Latitude
sanctchl <- xtractogon('erdVH3chlamday', xpos, ypos, tpos = tpos )
# }