转载：http://apps.hi.baidu.com/share/detail/24119344

hdf (hierarchical data format) 中文可译为分级数据格式，卫星资料多用这种形势存储。

%----step one---------open file
s='D:\parter\ben\QS_XWGRD3_2006192.20070991754';
sd_id = hdfsd('start',s,'read');
        % sd_id is the identifier of SD file
        %read-read access ,create-create a new access ,rdwr or write-read and write
        �cess

%----step two---------find the information
[ndatasets,nglobal_attr,status] = hdfsd('fileinfo',sd_id);
        % HDF4 file contains ndatasets data sets and nglobal_attr global attribute.
        % status 表示状态 vaule=-1 denote unsuccessful
       
%----step three--------get an file attibutes
    % for i=0:nglobal_attr-1;      
     %    [attr, status] = hdfsd('readattr', sd_id, i);
     % 知道索引号,求其对应的全局变量名（文件）
   % end
%sds_idx1=hdfsd('findattr',sd_id,'date_of_average')
            %－－－得到（findattr)sd_sds的sttr属性的文件号－－－－－－－
%[date_ave,status]=hdfsd('readattr',sd_id,sds_idx1)
            %－－－打开（readattr）sds_idx1对应的属性－－－－－－－－－－－－－－－－－
�cha=date_ave(7:15);

%scale
%size(double(scale))

%-------------step four,five.six,seven----------------------------------
for i=0:ndatasets-1             %---i相当于sds_idx-------
%for i=0:0      
     sds_id = hdfsd('select',sd_id,i);% To select a data set (i)
         % sds_id is HDF SD data set identifiers
     [scale, status] = hdfsd('readattr', sds_id, 0); %读对应变量的属性(scale)
     [offset,status]=hdfsd('readattr', sds_id, 2); %读对应变量的属性(offest),订正值
         %-get data set information----------
     [ds_name, ds_ndims, ds_dims, ds_type, ds_atts, stat]=...
     hdfsd('getinfo',sds_id);
         %----------------数组初始化-------------------
    ds_start = zeros(1,ds_ndims); % Creates the vector [0 0]
    ds_stride = [];
    ds_edges = ds_dims;
         %----------------read data set-----------------------
    [ds_data, status] =hdfsd('readdata',sds_id,ds_start,ds_stride,ds_edges);
         %----------------转换量级和订正
    ds_data=double(scale)*double(ds_data)-double(offset) ;
         %---------------文件输出----------------------
    s='D:\parter\ben\';
    s=[s ds_name '.dat'];
    fid=fopen(s,'w');
    fwrite(fid,ds_data,'float32');
    fclose(fid);
    stat = hdfsd('endaccess',sds_id);   % close data set
end
hdfsd('end',sd_id);   % close file

综合上述，主要由以下几个函数关于hdfsd函数

1。'readattr' 读其对应值（文件(sd_id)，数据（sds_id))的属性

2。   select 返回一个整数值sds_id = hdfsd('select',sd_id,i); 选择数据

3。'readdata' 读数据hdfsd('readdata',sds_id,ds_start,ds_stride,ds_edges);

4。'getinfo'获得数据的信息

5。'fileinfo'获得文件信息
6。hdfsd('start',s,'read'); 获得一个读hdf文件的文件号