How to explore and use the contents of a .sav file in IDL?

 

Before restoring a .sav file which is only including variables you may want to explore its content first. This is possible using the IDL_Savefile object class:  https://www.nv5geospatialsoftware.com/docs/IDL_Savefile.html 
 

; choose your .sav file
savefile = "C:\Path\to\your\Sav\File\sav_file.sav"
// or by selecting the file with:    savefile=dialog_pickfile()  

; create the IDL_Savefile object from this .sav file and query its content
sObj = OBJ_NEW('IDL_Savefile', savefile)
sObj.contents()

; output of the content:

{
    "FILENAME": "C:\Path\to\your\Sav\File\sav_file.sav",
    "DESCRIPTION": "",
    "FILETYPE": "Portable (XDR)",
    "USER": "username",
    "HOST": "hostname",
    "DATE": "Tue Aug 12 10:42:43 2025",
    "ARCH": "x86_64",
    "OS": "Win32",
    "RELEASE": "9.1.0",
    "N_COMMON": 0,
    "N_VAR": 0,
    "N_SYSVAR": 0,
    "N_PROCEDURE": 2877,
    "N_FUNCTION": 2025,
    "N_OBJECT_HEAPVAR": 0,
    "N_POINTER_HEAPVAR": 0,
    "N_STRUCTDEF": 0
}

 

; it is also possible to access the number of variables included in this .sav file ; as well as the variable names ; e.g.
print,content.N_VAR
foreach Name, sObj.Names() do print,Name,sObj.size(Name)

; you can then decide to restore only specific variables based on their names
data=sObj.Names()
sObj.restore,(data[0])

 

; another useful option is to convert specific variable names into a variable identifier using SCOPE_VARFETCH, so you can then manipulate this variable in your IDL code afterwards

b=SCOPE_VARFETCH(data[0])

help,b

 

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Created by BC on 1/19/21; modified by MT on 08/12/25

Reviewed by BC(US) on 1/21/2021