HDF和netCDF的差别（由图有真相）

沙颖凯

今天下数据发现同时有HDF和netCDF

AIRS dataprocess

然后我都下了，结果高下立判：

nc v.s. HDF

我记得HDF5和netCDF4在某种程度上是“等价”的，具体说不清。不过这里是HDF4。直观上看HDF的压缩程度明显比netCDF高，便于数据储存。可能这也是为什么MATLAB在R2006B之后使用HDF类型的mat文件存储数据了吧。

沙颖凯

imgrus 发表于 2014-11-13 07:54
取决于你的应用目的
用于存储，当然压缩率高节约资源
但是用于计算的时候，无压缩的更快

google了一下，netCDF4可以使用HDF5 lib压缩，看来只是这网站没有提供有压缩的netCDF。

模式使用netCDF我想是因为netCDF的维数可以是UNLIMITED， 而且不需要metadata。遥感数据使用HDF可能是因为HDF压缩算法效率更高，不是很确定。

imgrus

取决于你的应用目的
用于存储，当然压缩率高节约资源
但是用于计算的时候，无压缩的更快
比如有些数值模式会把nc4的驱动数据先转成nc3
跑完后的结果归档再转回nc4

新起点新生活

请问使用ncdump把netcdf4转换为3的么

yupo_smart

新起点新生活 发表于 2014-11-17 15:27
请问使用ncdump把netcdf4转换为3的么

NetCDF网站上的回答：

http://www.unidata.ucar.edu/software/netcdf/docs/faq.html#fv14

How can I convert netCDF-4 files into netCDF-3 files?

In general, you can't, because netCDF-4 files may have features of the netCDF enhanced data model, such as groups, compound types, variable-length types, or multiple unlimited dimensions, for which no netCDF-3 representation is available. However, if you know that a netCDF-4 file conforms to the classic model, either because it was written as a netCDF-4 classic model file, because the program that wrote it was a netCDF-3 program that was merely relinked to a netCDF-4 library, or because no features of the enhanced model were used in writing the file, then there are several ways to convert it to a netCDF-3 file.

You can use the nccopy utility from netCDF versions 4.1 and later. For example to convert a netCDF-4 classic-model format file foo4c.nc to a classic format file foo3.nc, use:

     nccopy -k classic foo4c.nc foo3.nc
If you have installed NCO , the NCO utility "ncks" can be used to accomplish the same task, as follows:

     ncks -3 foo4c.nc foo3.nc
For a relatively small netCDF-4 classic model file, "small4c.nc" for example, you can also use the ncdump and ncgen utilities to create an equivalent netCDF-3 classic format file named "small3.nc" as follows:

  ncdump small4c.nc > small4.cdl
  ncgen -o small3.nc small4.cdl

小虫小虫

yupo_smart 发表于 2014-11-18 16:49
NetCDF网站上的回答：

http://www.unidata.ucar.edu/software/netcdf/docs/faq.html#fv14

{:eb348这个看完，貌似知道了点。

黎大页子

沙颖凯 发表于 2014-11-14 07:35
google了一下，netCDF4可以使用HDF5 lib压缩，看来只是这网站没有提供有压缩的netCDF。

模式使用netCD ...

卫星数据用HDF格式储存更加高效
具体可见HDF格式的介绍 http://hdfgroup.org/why_hdf/
还有为气象卫星数据加了地理信息的HDF-EOS格式 http://nsidc.org/data/hdfeos/intro.html

rexienanhai

不错的贴子！

denote123

学习了 谢谢分享

zjlyb

{:5_235:}