HDF_SD_GETINFO

The HDF_SD_GETINFO procedure retrieves information about an SD dataset.

Note: Reading a label, unit, format, or coordinate system string that has more than 256 characters can have unpredictable results.

Examples

For an example using this routine, see the documentation for HDF_SD_SETINFO.

Syntax

HDF_SD_GETINFO, SDdataset_id [, CALDATA=variable] [, COORDSYS=variable] [, DIMS=variable] [, FILL=variable] [, FORMAT=variable] [, HDF_TYPE=variable] [, LABEL=variable] [, NAME=variable] [, NATTS=variable] [, NDIMS=variable] [, /NOREVERSE] [, RANGE=variable] [, TYPE=variable] [, UNIT=variable]

Arguments

SDdataset_id

An SD dataset ID as returned by HDF_SD _SELECT or HDF_SD_CREATE.

Keywords

CALDATA

Set this keyword to a named variable in which the calibration data associated with the SD dataset is returned. The data is returned in a structure of the form:

For more information about calibration data, see the documentation for HDF_SD_SETINFO.

COORDSYS

Set this keyword to a named variable in which the coordinate system description string is returned.

DIMS

Set this keyword to a named variable in which the dimensions of the SD dataset are returned. For efficiency, these dimensions are returned in reverse order from their HDF format unless the NOREVERSE keyword is also set.

FILL

Set this keyword to a named variable in which the fill value of the SD dataset is returned. Note that a fill value must be set in the SD dataset. If a fill value is not set, the value of the variable named by this keyword will be undefined, and IDL will issue a warning message.

FORMAT

Set this keyword to a named variable in which the format description string is returned. If the format description string is not present, this variable will contain an empty string.

HDF_TYPE

Set this keyword to a named variable in which the HDF type of the SD dataset is returned as a scalar string. Possible returned values are DFNT_NONE, DFNT_CHAR8, DFNT_FLOAT32, DFNT_FLOAT64, DFNT_INT8, DFNT_INT16, DFNT_INT32, DFNT_UINT8, DFNT_UINT16, and DFNT_UINT32.

Note: IDL does not have a signed 8-bit integer type. When writing the data to the file using DFNT_INT8, byte values from 0-127 will be written unchaged, while byte values from 128-255 will be wrapped into the range -127 to -1. When reading data of type DFNT_INT8 from the file into IDL, values from 0-127 will be read in unchanged, while values from -127 to -1 will be wrapped into the byte range 128 to 255.

LABEL

Set this keyword to a named variable in which the label description string is returned. If the label description string is not present, this variable will contain an empty string.

NAME

Set this keyword to a named variable in which the SD dataset name is returned. If the SD dataset name is not present, this variable will contain an empty string.

NATTS

Set this keyword to a named variable in which the number of “NetCDF-style” attributes for the SD dataset is returned.

NDIMS

Set this keyword to a named variable in which the number of dimensions in the dataset is returned.

NOREVERSE

Set this keyword in conjunction with DIMS to return the variable dimensions in non-reversed form. By default, IDL reverses data and dimensions from the HDF format to improve efficiency.

RANGE

Set this keyword to a named variable in which the maximum and minimum of the current SD dataset is returned as a two-element vector. Note that a range must be set in the SD dataset. If the range is not set, the value of the variable named by this keyword will be undefined, and IDL will issue a warning message.

TYPE

Set this keyword to a named variable in which the IDL type of the SD dataset is returned as a scalar string. Possible returned values are BYTE, INT, LONG, FLOAT, DOUBLE, STRING, or UNKNOWN.

UNIT

Set this keyword to a named variable in which the unit description string is returned. If the unit description string is not present, this variable will contain an empty string.

Version History

4.0	Introduced