ncmeta package provides straightforward NetCDF metadata, with a set of consistent entity-based functions for extracting metadata from a file or online source. We aim to fill a gap in between the generality and power of the NetCDF framework and the availability of easy to use modern software tools.
There are two main packages for using NetCDF in R,
ncdf4 and ncmeta use both of them, for subtle situations. Both packages are very close the native API of NetCDF itself, and ncmeta simply provides an easier high-level interpretation.
NetCDF is both a data model and an API, and provides a very general framework for expressing data formats. The explicit entities in NetCDF are variables, dimensions and attributes and ncmeta provides functions
nc_atts to extract their names, order and other metadata. There are matching functions
nc_att with an extra identifier argument that extract specific information about individual an variable, dimension, or attribute.
Ncmeta includes functions for implicit entities, these are grids and axes. These don’t exist in the NetCDF specification explicitly, but are meaningful and we think worth making explicit.
A grid is an ordered set of dimensions, and the Unidata site refers informally to this concept as shape. Many NetCDF tools don’t explicitly present these shapes, or grids so we are a little tentative in our definitions.
An axis is an instance of a dimension, the use of that dimension within a particular variable.
Together these entities provide a more developer-friendly scheme for working with the range of formats provided by the NetCDF ecosystem.
Install ncmeta from CRAN with:
You can install the development version of ncmeta from github with:
# install.packages("devtools") devtools::install_github("hypertidy/ncmeta")
This example shows some of the functions for extracting information from a NetCDF source.
library(ncmeta) filename <- system.file("extdata", "S2008001.L3m_DAY_CHL_chlor_a_9km.nc", package = "ncmeta") nc_inq(filename) # one-row summary of file nc_dim(filename, 0) ## first dimension nc_dims(filename) ## all dimensions
Please let us know if you have any feedback, see the Issues tab if you found a bug or have a question. Feel free to email the maintainer directly for other questions.
Please note that this project is released with a Contributor Code of Conduct. By participating in this project you agree to abide by its terms.