Help with 'pattern' in Python syntax

[Ruben Geert van den Berg]

Dear all,
 
I've a data file with groups of variables. They look like
 
n1_1 n1_2 n1_3
n2_1 n2_2
n3_1 n3_2 n3_3 n3_4
 
and so on. I want to build syntax based on the first subscript of n. The range of the second subscript differs between groups (so n1 may run up to n1_5 while n2 may run up to n2_7). So I try to make variable lists like
 
n1_1 to n1_i
n2_1 to n2_j
 
and so on. I've 7 groups and I tried to loop (1 through 7) and put the loop variable into a pattern statement but I don't master enough Python to get it done. My attempt, so far, is
 
begin program.
import spss,spssaux
for i in range(7):
    for j in range(spss.GetVariableCount()):
        varlist=spssaux.VariableDict(pattern = "n"+str[i+1]+"_\d+")
        print varlist
end program.
 
And the result is
 

Traceback (most recent call last):

File "<string>", line 5, in <module>

TypeError: 'type' object is unsubscriptable

 
Could anyone please propose a Python statement that will do the job?
 
TIA,

Ruben van den Berg
Consultant Models & Methods
TNS NIPO
Email: [hidden email]
Mobiel: [phone]
Telefoon: [phone]
Internet: www.tns-nipo.com

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[Jon K Peck]

Jon Peck
SPSS, an IBM Company
[hidden email]
312-651-3435

From:	Ruben van den Berg <[hidden email]>
To:	[hidden email]
Date:	07/02/2010 02:44 AM
Subject:	[SPSSX-L] Help with 'pattern' in Python syntax
Sent by:	"SPSSX(r) Discussion" <[hidden email]>

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Dear all,

I've a data file with groups of variables. They look like

n1_1 n1_2 n1_3
n2_1 n2_2
n3_1 n3_2 n3_3 n3_4

and so on. I want to build syntax based on the first subscript of n. The range of the second subscript differs between groups (so n1 may run up to n1_5 while n2 may run up to n2_7). So I try to make variable lists like

n1_1 to n1_i
n2_1 to n2_j

and so on. I've 7 groups and I tried to loop (1 through 7) and put the loop variable into a pattern statement but I don't master enough Python to get it done. My attempt, so far, is

begin program.
import spss,spssaux
for i in range(7):
   for j in range(spss.GetVariableCount()):
       varlist=spssaux.VariableDict(pattern = "n"+str[i+1]+"_\d+")
       print varlist
end program.

And the result is

Traceback (most recent call last):
File "<string>", line 5, in <module>
TypeError: 'type' object is unsubscriptable

>>>The immediate problem is that str is a function, but this code is subscripting it - square brackets vs parentheses.

But the larger problem is that you are creating a variable dictionary for each input variable and each pattern.  BTW, when you print it, you will just get a variable dictionary object printed.  To see what variables you are creating, change the print statement to
print varlist.variables
You will see that the code creates each variable list seven times.
Try something like this,

begin program.
import spss,spssaux
vardict = spssaux.VariableDict()
for i in range(3):  #number of groups
  varlist = vardict.range(pattern="n" + str(i+1) + r"_\d+")
  print varlist
end program.

First a variable dictionary is created.  (You could make it a subset of the variables starting with n by using pattern="n" in the VariableDict call.)
Then the range method of the variableDict object is called to select a subset of the variables in the vardict dictionary.  Note that I used r in front of the last part of the pattern string.  It isn't necessary here, but it prevents Python from treating \x sequences as escape sequences and ensures that \d is left to be interpreted as regular expression notation.

HTH,
Jon Peck

 
Could anyone please propose a Python statement that will do the job?

TIA,

Ruben van den Berg
Consultant Models & Methods
TNS NIPO
Email: [hidden email]
Mobiel: [phone]
Telefoon: [phone]
Internet: www.tns-nipo.com

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