HDF_SD_SETINFO

The HDF_SD_SETINFO procedure sets information about an SD dataset.

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

Examples

; Open an HDF file:

SDinterface_id = HDF_SD_START('demo.hdf', /RDWR)

; Define a new dataset for the file:

SDdataset_id = HDF_SD_CREATE(SDinterface_id, 'variable1', [10, 20], /DOUBLE)

; Create a calibration data structure:

CAL={Cal:1.0D, Cal_Err:0.1D, Offset:2.5D, Offset_Err:0.1D, $

   Num_Type:6L}

; Set information about the dataset:

HDF_SD_SETINFO, SDdataset_id, LABEL='label1', unit='unit1', $

   format='format1', coordsys='coord1', FILL=999.991, $

   RANGE=[99.99,-78], caldata=CAL

; Retrieve the information:

HDF_SD_GETINFO, SDdataset_id, LABEL=l, UNIT=u, FORMAT=f, $

   COORDSYS=c, FILL=fill, RANGE=r, CALDATA=cd, $

   NDIMS=ndims, DIMS=dims, TYPE=ty

; Print information about the returned variables:

HELP, l, u, f, c, fill, r, cd, ndims, dims, ty

; Print the range:

PRINT, r

; Print the calibration data:

PRINT, cd

; Print the dimensions:

PRINT, dims

; Close the SD interface:

HDF_SD_ENDACCESS, SDdataset_id

HDF_SD_END, SDinterface_id

IDL Output

L STRING = 'label1'

U STRING = 'unit1'

F STRING = 'format1'

C STRING = 'coord1'

FILL DOUBLE = 999.99103

R DOUBLE = Array(2)

CD STRUCT = -> < Anonymous > Array(1)

NDIMS LONG = 2

DIMS LONG = Array(2)

TY STRING = 'DOUBLE'

-78.000000 99.989998

{ 1.0000000 0.10000000 2.5000000 0.10000000 6}

10 20

Syntax

HDF_SD_SETINFO, SDdataset_id [, CALDATA=structure] [, COORDSYS=string] [, FILL=value] [, FORMAT=string] [, LABEL=string] [, RANGE=[max, min]] [, UNIT=string]

Arguments

SDdataset_id

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

Keywords

CALDATA

Set this keyword to a structure that contains the calibration data. This structure must contain five tags as shown below. The first four tags are of double-precision floating-point type. The fifth tag should be a long integer that specifies the HDF number type. The structure should have the following form:

CALDATA={ Cal: 0.0D $         ;Calibration Factor

      Cal_Err: 0.0D $         ;Calibration Error

       Offset: 0.0D $         ;Uncalibrated Offset

       Offset_Err: 0.0D $     ;Uncalibrated Offset Error

       Num_Type: 0L }          ;Number Type of Uncalibrated Data

The relationship between HDF and IDL number types is illustrated by the following table:

HDF Number Type	IDL Data Type
0L	UNDEFINED
3L	STRING
21L	BYTE
22L	INTEGER
24L	LONG INTEGER
5L	FLOATING-POINT
6L	DOUBLE-PRECISION

The relationship between the calibrated data (CD) and the uncalibrated data (UD) is given by the equation:

CD = Cal * (UD - Offset)

Cal and Offset are the values of the Cal and Offset structure fields described above.

COORDSYS

Set this keyword to a string to be used as the SD dataset coordinate system.

FILL

Set this keyword to the fill value of the SD dataset.

FORMAT

Set this keyword to a string to be used as the SD dataset format.

LABEL

Set this keyword to a string to be used as the SD dataset label.

RANGE

Set this keyword to a two dimensional array that contains the minimum and maximum values of the SD dataset.

UNIT

Set this keyword to a string to be used as the SD dataset units.

Version History

4.0	Introduced