In NetCDF, variables are defined along dimensions and are said to have "coordinate variables" that define the (typically spatio-temporal) positions of the data's cells.
nc_coord_var(x, variable = NULL, ...)
# S3 method for character
nc_coord_var(x, variable = NULL, ...)
# S3 method for NetCDF
nc_coord_var(x, variable = NULL, ...)NetCDF source
variable name of interest. If not included, all variables will be returned.
ignored
tibble with "variable", "X", "Y", "Z", "T", and "bounds" columns that reference variables by name.
This function attempts to identify the X, Y, Z, and T coordinate variables for each data variable in the provided NetCDF source. The NetCDF-CF attribute conventions are used to make this determination.
All variables that can be related to a spatio-temporal axis, including coordinate variables are returned. For coordinate variables, a "bounds" column is included in the response indicating which variable contains bounds information.
See http://cfconventions.org/cf-conventions/v1.6.0/cf-conventions.html#coordinate-system for more.
f <- system.file("extdata", "S2008001.L3m_DAY_CHL_chlor_a_9km.nc", package = "ncmeta")
nc_coord_var(f, "chlor_a")
#> # A tibble: 1 × 6
#> variable X Y Z T bounds
#> <chr> <chr> <chr> <chr> <chr> <chr>
#> 1 chlor_a lon lat NA NA NA
f <- system.file("extdata", "guam.nc", package = "ncmeta")
nc_coord_var(f)
#> # A tibble: 5 × 6
#> variable X Y Z T bounds
#> <chr> <chr> <chr> <chr> <chr> <chr>
#> 1 RAINNC_present XLONG XLAT NA Time NA
#> 2 Time NA NA NA Time time_bnds
#> 3 T2_present XLONG XLAT NA Time NA
#> 4 U10_present XLONG XLAT NA Time NA
#> 5 V10_present XLONG XLAT NA Time NA