Command depends on existence of a var.sps

 

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* Check existence of a given variable in SPSS with Python script.

* Command to be executed depends on the existence of a given variable.
* Format is "varname ; command if varname exists; command if it does not exist"
* Raynald Levesque  www.spsstools.net  2005/10/11.

GET FILE='c:\program files\spss\employee data.sav'.
COMPUTE VarA = 3 .

HOST COMMAND=['ECHO VarA; COMPUTE VarA=2*VarA .; COMPUTE VarA=1.> c:\temp\varExists.txt'].

* The above HOST COMMAND creates a text file to pass parameters to the python script. 
* Parameters are delimited by ";" Each command must end with a ".".
* The above varExists.txt file means that 
*  if VarA exists, the command in the 2nd parameter "COMPUTE VarA=2*VarA." will be executed.
*  if VarA does NOT exist, the command in the 3rd parameter "COMPUTE VarA=1" will be executed.
* Macro calls or INSERT FILE commands could also be used instead of the simple commands used above.

*------------------------------.
BEGIN PROGRAM python.

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import spss, win32api

try:
	f = open(r'c:\temp\varExists.txt','r')
	s = f.readline()
	f.close()
	win32api.DeleteFile(r'c:\temp\varExists.txt')
except:
	print "\n ***Error by Python script"	

if f and s:	
	vec = s.split(";")
	varExists = 0
	for i in range( spss.GetVariableCount() ):
		varName = spss.GetVariableName(i)
		if varName.upper() == vec[0].upper():
			varExists = 1
			print "\n*** variable exists"	
			break 
	if varExists == 0 and vec[2].strip() <> "":
		spss.Submit(vec[2])
		print "\n*** variable did NOT exist"
	elif varExists == 1 and vec[1].strip <> "":
		spss.Submit(vec[1])

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END PROGRAM.
*------------------------------.

EXECUTE.

**************************************************************************************.
* Short command version (that is a version that is easy to use on a DAILY BASIS).
* the above python program is saved in "c:\temp\varExists.sps".

* Include the following macro in the macro.sps file.
*////////////////////////////.
DEFINE !VarExists(!POS=!CMDEND)
HOST COMMAND=[!QUOTE(!CONCAT('ECHO ',!UNQUOTE(!1), !UNQUOTE('> c:\temp\varExists.txt')))].
INSERT FILE="c:\temp\varExists.sps".
!ENDDEFINE.
*////////////////////////////.

* Example 1: variable exists.

GET FILE='c:\program files\spss\employee data.sav'.
COMPUTE VarA=2.
!VarExists "VarA; FREQ VAR=VarA .; COMPUTE VarA=1.".
EXECUTE.

* Example 2: when variable does not exist.

GET FILE='c:\program files\spss\employee data.sav'.
!VarExists "VarA; FREQ VAR=VarA .; COMPUTE VarA=1.".
EXECUTE.

* Example 3: multiline commands.
* Use macros to define what needs to be done in each case.

DEFINE !whenExist()
COMPUTE VarA = VarA * 2.
FREQ VAR = VarA
!ENDDEFINE.

DEFINE !whenNotExist()
COMPUTE VarA = 3.
TITLE "varA did not exist".
!ENDDEFINE.

GET FILE='c:\program files\spss\employee data.sav'.
!VarExists "VarA; !whenExist .; !whenNotExist.".
EXECUTE.
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