CDF_ATTPUT
Syntax | Arguments | Keywords | Examples | Version History
The CDF_ATTPUT procedure writes an attribute entry to a Common Data Format file, or attaches an attribute to a CDF variable. If the specified entry already exists, it is overwritten.
Syntax
CDF_ATTPUT, Id, Attribute, EntryNum, Value [, /ZVARIABLE]
Arguments
Id
The CDF ID, returned from a previous call to CDF_OPEN or CDF_CREATE.
Attribute
A string containing either the name or number of the attribute to be written.
EntryNum
The entry number. If the attribute is variable in scope, this is either the name or number of the variable the attribute is to be associated with. If the attribute is global in scope, this is the actual gEntry. It is the user's responsibility to keep track of valid gEntry numbers. Normally gEntry numbers will begin with 0 or 1 and will increase up to MAXGENTRY (as reported in the GET_ATTR_INFO structure returned by CDF_CONTROL), but this is not required.
Value
The value(s) to be written.
Keywords
ZVARIABLE
If EntryNum is a variable ID (as opposed to a variable name) and the variable is a zVariable, set this flag to indicate that the variable ID is a zVariable ID. The default is to assume that EntryNum is an rVariable ID. Note: the attribute must have a scope of VARIABLE_SCOPE.
Examples
Example 1
Id= CDF_CREATE('foo', /SUN_ENCODING, /HOST_DECODING, $
/ROW_MAJOR) ; no dimensions.
dummy= CDF_VARCREATE(id, 'Var1', /CDF_INT4, /REC_VARY)
v2= CDF_VARCREATE(id, 'Var2', /CDF_FLOAT, /REC_NOVARY)
dummy= CDF_ATTCREATE(id, 'Title', /VARIABLE)
global_dummy = CDF_ATTCREATE(id,'Date',/GLOBAL)
dummy= CDF_ATTCREATE(id, 'Att2', /VARIABLE)
CDF_ATTPUT, id, 'Title', 'Var1', 'Temperature at surface'
CDF_ATTPUT, id, 'Title', v2, 'Time of recording'
CDF_ATTPUT, id, 'Date',1,'July 4, 1996'
CDF_ATTPUT, id, 'Att2', 'Var2', FINDGEN(10)
; Rename the "Att2" attribute to "Attribute2":
CDF_ATTRENAME, Id, 'Att2', 'Attribute2'
; Verify the attribute number (zero-based) of Attribute2
PRINT, CDF_ATTNUM(id, 'Attribute2')
; Close the CDF file. This file is used in the CDF_ATTGET example.
CDF_CLOSE, id
IDL Output
Example 2
The following example uses the Global attribute "MODS" to keep track of the modification history of a CDF file named mods.cdf.
id = CDF_CREATE('mods.cdf', /CLOBBER)
cid = CDF_ATTCREATE(id, 'MODS', /GLOBAL_SCOPE)
CDF_ATTPUT, id, cid, 0, 'Original Version'
CDF_CLOSE, id
; Next, reopen the CDF file and make modifications:
id = CDF_OPEN('mods.cdf')
CDF_CONTROL, id, ATTRIBUTE='MODS', GET_ATTR_INFO=ginfo
;Use CDF_CONTROL to get the MAXGENTRY used.
CDF_ATTPUT, id, cid, ginfo.maxgentry+1,'Second Version'
;Insert the new gEntry at MAXGENTRY+1.
CDF_CLOSE, id
; Reopen the CDF file again and make more modifications:
id = CDF_OPEN('mods.cdf')
CDF_CONTROL, id, ATTRIBUTE='MODS', GET_ATTR_INFO=ginfo
CDF_ATTPUT, id, cid, ginfo.maxgentry+1, 'Third Version'
CDF_CLOSE, id
;Reopen the CDF file again and make a modification in the
;MAXGENTRY + 2 spot (skipping an entry number).
id = CDF_OPEN('mods.cdf')
CDF_CONTROL, id, ATTRIBUTE='MODS', GET_ATTR_INFO=ginfo
CDF_ATTPUT, id, cid, ginfo.maxgentry+2, 'Fourth Version'
; Now, examine the CDF file to review its modification history.
; Since the gENTRY numbers have a gap in them, we can check each
; attribute with the CDF_ATTEXISTS function. This is a good idea
; if you do not know for certain that the attribute entries are
; serially numbered.
CDF_CONTROL, id, ATTRIBUTE='MODS', GET_ATTR_INFO=ginfo
FOR I=0, ginfo.maxgentry DO BEGIN
IF CDF_ATTEXISTS(id, cid, I) THEN BEGIN
CDF_ATTGET, id, cid, I, gatt
PRINT, I, gatt, FORMAT='("Attribute: MODS (gENTRY #",i1,") = ",A)'
ENDIF ELSE BEGIN
PRINT, I, FORMAT='("Attribute: MODS (gENTRY #",i1,") $
Does not exist")'
ENDELSE
ENDFOR
CDF_CLOSE, id
IDL Output
Attribute: MODS (gENTRY #0) = Original Version Attribute: MODS (gENTRY #1) = Second Version Attribute: MODS (gENTRY #2) = Third Version Attribute: MODS (gENTRY #3) Does not exist Attribute: MODS (gENTRY #4) = Fourth Version
Version History
