PRO HDF_SD_VARREAD, HDFID, VARNAME, DATA, _EXTRA=EXTRA_KEYWORDS;+; NAME:;    HDF_SD_VARREAD;; PURPOSE:;    Read data from a Scientific Data Set (SDS) variable;    in a HDF file.;; CATEGORY:;    HDF utilities.;; CALLING SEQUENCE:;    HDF_SD_VARREAD, HDFID, VARNAME, DATA;; INPUTS:;    HDFID       Identifier of HDF file opened by caller with HDF_SD_START.;    VARNAME     Name of Scientific Data Set variable.;; OPTIONAL INPUTS:;    None.;; KEYWORD PARAMETERS:;    START       Set this keyword to a vector containing the start position;                for the read in each dimension;                (default start position is [0, 0, ..., 0]).;    COUNT       Set this keyword to a vector containing the number of items;                to be read in each dimension;                (default is to read all available data).;    STRIDE      Set this keyword to a vector containing the sampling interval;                along each dimension;                (default stride vector for a contiguous read is [0, 0, ..., 0]).;    NOREVERSE   Set the keyword to retrieve the data without transposing the;                data from column to row order.;; OUTPUTS:;    DATA        Named variable in which data will be returned;                (degenerate dimensions are removed).;; OPTIONAL OUTPUTS:;    None;; COMMON BLOCKS:;    None;; SIDE EFFECTS:;    None.;; RESTRICTIONS:;    Requires IDL 5.0 or higher (square bracket array syntax).;; EXAMPLE:;;file = 'sdsvdata.hdf';hdfid = hdf_sd_start(file);hdf_sd_varread, hdfid, '2D integer array', data;hdf_sd_end, hdfid;help, data;; MODIFICATION HISTORY:; Liam.Gumley@ssec.wisc.edu; http://cimss.ssec.wisc.edu/~gumley; $Id: hdf_sd_varread.pro,v 1.1.1.1 2005/06/09 20:04:48 kathys Exp $;; Copyright (C) 1999, 2000 Liam E. Gumley;; This program is free software; you can redistribute it and/or; modify it under the terms of the GNU General Public License; as published by the Free Software Foundation; either version 2; of the License, or (at your option) any later version.;; This program is distributed in the hope that it will be useful,; but WITHOUT ANY WARRANTY; without even the implied warranty of; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the; GNU General Public License for more details.;; You should have received a copy of the GNU General Public License; along with this program; if not, write to the Free Software; Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.;-rcs_id = '$Id: hdf_sd_varread.pro,v 1.1.1.1 2005/06/09 20:04:48 kathys Exp $';- Check argumentsif (n_params() ne 3) then message, 'Usage: HDF_SD_VARREAD, HDFID, VARNAME, DATA'if (n_elements(hdfid) eq 0) then message, 'Argument HDFID is undefined'if (n_elements(varname) eq 0) then message, 'Argument VARNAME is undefined'if (arg_present(data) eq 0) then message, 'Argument VARDATA cannot be modified';- Get index for this variableindex = hdf_sd_nametoindex(hdfid, varname)if (index eq -1) then $  message, string(varname, format='("VARNAME not found: ", a)');- Select the variable and read the datavarid = hdf_sd_select(hdfid, index)hdf_sd_getdata, varid, data, _extra=extra_keywordshdf_sd_endaccess, variddata = reform(temporary(data))END