Utilities for the NcFile class

Collaboration diagram for Utilities for the NcFile class:

Classes
struct	dg::file::NC_Error
	Class thrown by the NC_Error_Handle. More...
struct	dg::file::NcHyperslab
	A NetCDF Hyperslab for SerialNcFile. More...
struct	dg::file::MPINcHyperslab
	A NetCDF Hyperslab for MPINcFile. More...
struct	dg::file::LongNameAttribute
	Facilitate construction of CF attribute "long_name" in records lists. More...
struct	dg::file::Record< SignatureType, Attributes >
	A realisation of the Record concept. Helper to generate NetCDF variables. More...

Typedefs
using	dg::file::nc_att_t
	Utility type to simplify dealing with heterogeneous attribute types.
template<class Signature >
using	dg::file::get_first_argument_type_t = std::decay_t<typename detail::get_first_argument_type<Signature>::type>
template<class Signature >
using	dg::file::get_result_type_t = typename std::function<Signature>::result_type

Enumerations
enum	dg::file::NcFileMode { dg::file::nc_nowrite , dg::file::nc_write , dg::file::nc_clobber , dg::file::nc_noclobber }
	NetCDF file format. More...

Functions
std::string	dg::file::timestamp (int argc, char *argv[])
	Generate one line entry for the history global attribute.

Variables
const std::map< std::string, std::string >	dg::file::version_flags
	Version compile time constants available as a map.

Detailed Description

Typedef Documentation

get_first_argument_type_t

template<class Signature >

using dg::file::get_first_argument_type_t = std::decay_t<typename detail::get_first_argument_type<Signature>::type>

If Signature = R(Arg1, A...) return Arg1

get_result_type_t

template<class Signature >

using dg::file::get_result_type_t = typename std::function<Signature>::result_type

If Signature = R(Arg1, A...) return R

nc_att_t

using dg::file::nc_att_t

Initial value:

 std::variant<int, unsigned, float, double, bool, std::string,
      std::vector<int>, std::vector<unsigned>, std::vector<float>,
      std::vector<double>, std::vector<bool>>

Utility type to simplify dealing with heterogeneous attribute types.

Note

Unfortunately, user defined types exist so not every attribute can be an nc_att_t

Enumeration Type Documentation

NcFileMode

enum dg::file::NcFileMode

NetCDF file format.

All Files are opened/ created in Netcdf-4 data format

Note

If you are looking for an "nc_append" you can use

auto nc_append = std::filesystem::exists(filename) ? nc_write : nc_noclobber;

Enumerator
nc_nowrite	NC_NOWRITE Open an existing file for read-only access, fail if it does not exist.
nc_write	NC_WRITE Open an existing file for read and write access, fail if it does not exist.
nc_clobber	NC_CLOBBER Create a new file for read and write access, overwrite if file exists.
nc_noclobber	NC_NOCLOBBER Create new file for read and write access, fail if already exists.

Function Documentation

timestamp()

std::string dg::file::timestamp ( int argc, char * argv[] )

inline

Generate one line entry for the history global attribute.

This will generate a string containing a whitespace seperated list of

1. the current UTC time in ISO 8601 format: Y-m-dTH:M:SZ
2. all given argv (whitespace separated)
3. A newline

        int argc = 2;
        char *argv[] = {
            (char*)"./netcdf_t",
            (char*)"input.json",
            NULL
        };
        file.put_att( {"history", dg::file::timestamp(argc, argv)});
        auto history = file.get_att_as<std::string>( "history");
        INFO("history "<<history);
        std::istringstream ss( history);
        std::tm t = {};
        ss >> std::get_time( &t, "%Y-%m-%dT%H:%M:%SZ");
        CHECK( not ss.fail());
        std::string program;
        ss >> program;
        INFO( "Program "<<program);
        CHECK( program == "./netcdf_t");
        std::string arg;
        ss >> arg;
        CHECK( arg == "input.json");
        CHECK( not ss.fail());

Parameters

argc	from main function
argv	from main function

Returns

string containing current time followed by the parameters with which the program was invoked

See also

See history in Attribute Convenctions

std::put_time

Variable Documentation

version_flags

const std::map<std::string, std::string> dg::file::version_flags

inline

Initial value:

=
{
 
    {"git_hash", GIT_HASH},
 
 
    {"git_branch", GIT_BRANCH},
 
 
    {"compile_time", COMPILE_TIME},
 
}

Version compile time constants available as a map.

Is intended to be used as NetCDF file attributes

        int argc = 2;
        char *argv[] = {
            (char*)"./netcdf_t",
            (char*)"input.json",
            NULL
        };
        file.put_att( {"history", dg::file::timestamp(argc, argv)});
        auto history = file.get_att_as<std::string>( "history");
        INFO("history "<<history);
        std::istringstream ss( history);
        std::tm t = {};
        ss >> std::get_time( &t, "%Y-%m-%dT%H:%M:%SZ");
        CHECK( not ss.fail());
        std::string program;
        ss >> program;
        INFO( "Program "<<program);
        CHECK( program == "./netcdf_t");
        std::string arg;
        ss >> arg;
        CHECK( arg == "input.json");
        CHECK( not ss.fail());

Note

We use underscore instead of "git-hash" so that python netcdf can more easily read the attribute

The entries in the map are filled only if the corresponding MACROs are defined at compile time. Use -DVERSION_FLAGS during compilation to define all otherwise it remains empty. This is the corresponding entry in feltor/config/version.mk

GIT_HASH=$(git rev-parse HEAD)
COMPILE_TIME=$(date -u +'%Y-%m-%dT%H:%M:%SZ')
GIT_BRANCH=$(git branch --show-current)

See also

This approach follows stackoverflow.