Python packages

Unit Tests

CDFpp (CDF++)

Installing

From PyPi

python3 -m pip install --user pycdfpp

From sources

meson buildcd buildninjasudo ninja install

python -m build.# resulting wheel will be located into dist folder

Basic usage

Python

Reading CDF files

importpycdfppcdf=pycdfpp.load("some_cdf.cdf")cdf_var_data=cdf["var_name"].values#builds a numpy view or a list of stringsattribute_name_first_value=cdf.attributes['attribute_name'][0]

importpycdfppimportrequestsimportmatplotlib.pyplotasplttha_l2_fgm=pycdfpp.load(requests.get("https://spdf.gsfc.nasa.gov/pub/data/themis/tha/l2/fgm/2016/tha_l2_fgm_20160101_v01.cdf").content)plt.plot(tha_l2_fgm["tha_fgl_gsm"])plt.show()

importpycdfppimportrequestsimportxarrayasxrimportmatplotlib.pyplotasplttha_l2_fgm=pycdfpp.load(requests.get("https://spdf.gsfc.nasa.gov/pub/data/themis/tha/l2/fgm/2016/tha_l2_fgm_20160101_v01.cdf").content)xr.DataArray(tha_l2_fgm['tha_fgl_gsm'],dims=['time','components'],coords={'time':tha_l2_fgm['tha_fgl_time'].values,'components':['x','y','z']}).plot.line(x='time')plt.show()# Works with matplotlib directly tooplt.plot(tha_l2_fgm['tha_fgl_time'],tha_l2_fgm['tha_fgl_gsm'])plt.show()

importpycdfppimportos# Due to an issue with pybind11 you have to force your timezone to UTC for# datetime conversion (not necessary for numpy datetime64)os.environ['TZ']='UTC'mms2_fgm_srvy=pycdfpp.load("mms2_fgm_srvy_l2_20200201_v5.230.0.cdf")# to convert any CDF variable holding any time type to python datetime:epoch_dt=pycdfpp.to_datetime(mms2_fgm_srvy["Epoch"])# same with numpy datetime64:epoch_dt64=pycdfpp.to_datetime64(mms2_fgm_srvy["Epoch"])# note that using datetime64 is ~100x faster than datetime (~2ns/element on an average laptop)

Writing CDF files

importpycdfppimportnumpyasnpfromdatetimeimportdatetimecdf=pycdfpp.CDF()cdf.add_attribute("some attribute", [[1,2,3], [datetime(2018,1,1),datetime(2018,1,2)],"hello\nworld"])cdf.add_variable(f"some variable",values=np.ones((10),dtype=np.float64))pycdfpp.save(cdf,"some_cdf.cdf")

C++

#include"cdf-io/cdf-io.hpp"#include<iostream>std::ostream&operator<<(std::ostream& os,const cdf::Variable::shape_t& shape){    os <<"(";for (auto i =0; i <static_cast<int>(std::size(shape)) -1; i++)        os << shape[i] <<',';if (std::size(shape) >=1)        os << shape[std::size(shape) -1];    os <<")";return os;}intmain(int argc,char** argv){auto path =std::string(DATA_PATH) +"/a_cdf.cdf";// cdf::io::load returns a optional<CDF>if (constauto my_cdf =cdf::io::load(path); my_cdf)    {        std::cout <<"Attribute list:" << std::endl;for (constauto& [name, attribute] : my_cdf->attributes)        {            std::cout <<"\t" << name << std::endl;        }        std::cout <<"Variable list:" << std::endl;for (constauto& [name, variable] : my_cdf->variables)        {            std::cout <<"\t" << name <<" shape:" << variable.shape() << std::endl;        }return0;    }return -1;}

caveats