Multidimensional raster API tutorial
Read the content of an array
#include "gdal_priv.h"
int main()
{
GDALAllRegister();
auto poDataset = std::unique_ptr<GDALDataset>(
GDALDataset::Open( "in.nc", GDAL_OF_MULTIDIM_RASTER ));
if( !poDataset )
{
exit(1);
}
auto poRootGroup = poDataset->GetRootGroup();
if( !poRootGroup )
{
exit(1);
}
auto poVar = poRootGroup->OpenMDArray("temperature");
if( !poVar )
{
exit(1);
}
size_t nValues = 1;
std::vector<size_t> anCount;
for( const auto poDim: poVar->GetDimensions() )
{
anCount.push_back(static_cast<size_t>(poDim->GetSize()));
nValues *= anCount.back();
}
std::vector<double> values(nValues);
poVar->Read(std::vector<GUInt64>{0,0,0}.data(),
anCount.data(),
nullptr, /* step: defaults to 1,1,1 */
nullptr, /* stride: default to row-major convention */
GDALExtendedDataType::Create(GDT_Float64),
&values[0]);
return 0;
}
#include "gdal.h"
#include "cpl_conv.h"
int main()
{
GDALDatasetH hDS;
GDALGroupH hGroup;
GDALMDArrayH hVar;
size_t nDimCount;
GDALDimensionH* dims;
size_t nValues;
size_t i;
size_t* panCount;
GUInt64* panOffset;
double* padfValues;
GDALExtendedDataTypeH hDT;
GDALAllRegister();
hDS = GDALOpenEx( "in.nc", GDAL_OF_MULTIDIM_RASTER, NULL, NULL, NULL);
if( !hDS )
{
exit(1);
}
hGroup = GDALDatasetGetRootGroup(hDS);
GDALReleaseDataset(hDS);
if( !hGroup )
{
exit(1);
}
hVar = GDALGroupOpenMDArray(hGroup, "temperature", NULL);
GDALGroupRelease(hGroup);
if( !hVar )
{
exit(1);
}
dims = GDALMDArrayGetDimensions(hVar, &nDimCount);
panCount = (size_t*)CPLMalloc(nDimCount * sizeof(size_t));
nValues = 1;
for( i = 0; i < nDimCount; i++ )
{
panCount[i] = GDALDimensionGetSize(dims[i]);
nValues *= panCount[i];
}
GDALReleaseDimensions(dims, nDimCount);
panOffset = (GUInt64*)CPLCalloc(nDimCount, sizeof(GUInt64));
padfValues = (double*)VSIMalloc2(nValues, sizeof(double));
if( !padfValues )
{
GDALMDArrayRelease(hVar);
CPLFree(panOffset);
CPLFree(panCount);
exit(1);
}
hDT = GDALExtendedDataTypeCreate(GDT_Float64);
GDALMDArrayRead(hVar,
panOffset,
panCount,
NULL, /* step: defaults to 1,1,1 */
NULL, /* stride: default to row-major convention */
hDT,
padfValues,
NULL, /* array start. Omitted */
0 /* array size in bytes. Omitted */);
GDALExtendedDataTypeRelease(hDT);
GDALMDArrayRelease(hVar);
CPLFree(panOffset);
CPLFree(panCount);
VSIFree(padfValues);
return 0;
}
from osgeo import gdal
ds = gdal.OpenEx("in.nc", gdal.OF_MULTIDIM_RASTER)
rootGroup = ds.GetRootGroup()
var = rootGroup.OpenMDArray("temperature")
data = var.Read(buffer_datatype = gdal.ExtendedDataType.Create(gdal.GDT_Float64))
# if NumPy is available we can use ReadAsArray
data = var.ReadAsArray(buffer_datatype = gdal.ExtendedDataType.Create(gdal.GDT_Float64))
Other examples
Test scripts from the GDAL autotest suite
MEM driver: memmultidim.py
netCDF driver: netcdf_multidim.py
HDF5 driver: hdf5multidim.py
VRT driver: vrtmultidim.py