get_navigation: Retrieve a navigation structure for extracting slabs.

In BigelowLab/nam218grads: Provides grads-served opendap access to NAM218 forecast data

Retrieve a navigation structure for extracting slabs.

Description

Handy if you are doing multiple extractions - just compute the extraction navigation once and resuse it (not that computing is slow.)

Usage

get_navigation(
  x,
  bb = get_bounds(x),
  time = get_loc(x, "time")[1:3],
  lev = get_loc(x, "lev")[1:5]
)

Arguments

x	ncdf4 object
bb	a 4 element bounding box for subsetting ordered as [xmin, xmax, ymin, ymax]
time	POSIXct vector of one or more times to retrieve. These are matched the closest known times in the object. See get_time Default is the first recorded time in the object.
lev	numeric vector of one or more levels. These are matched the closest known levels in the object. See get_lev Default is the first level time in the object. Ignored if lev is not a dimension of the variable.

Value

a list of extraction navigation elements

• obb, otime, olev: original request inputs

• ilon, ilat, itime, ilev: index into dimensions for obb, otime and olev

• lons, lats, times, levs: full real world dimension values

• dx, dy: x and y resolution

• xlim, ylim: limits envelope

• index: list of array (slab) indices as in [start, count] form

• stbb: st_bbox object

• time_index, lev_index: full sequential indices into times and levs

BigelowLab/nam218grads documentation built on Oct. 4, 2022, 2:01 a.m.