Date:         Fri, 21 Dec 2007 05:31:50 -0800
Reply-To:     Albert-jan Roskam <fomcl@yahoo.com>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         Albert-jan Roskam <fomcl@yahoo.com>
Subject:      Python: exporting a file to its string equivalent
In-Reply-To:  <002701c84389$ab712a40$02537ec0$@com>
Content-Type: text/plain; charset=iso-8859-1

Hi listers,

I am trying to learn Python and to practice I thought
it would be nice to write a program that converts all
numeric variables to string. This might come in handy
when I use disease code classification and I export
those to xls. I've noticed several times that Excel
has the annoying habit to 'abbreviate' e.g. code 00001
to 1. This could have a completely different meaning!

For now I want to convert F and N type variables to
their string equivalents. Maybe the code below is
overly complicated already, but I just wanted to try
the various Python commands.

I have some questions about the code I wrote:

Ad ## 1 ## Not all variables are converted to string.
It's like the IF-ELIF jumps too soon to the next step.

How come?

Ad ## 2 ## Minor nuisance: how can the list of
variables be numbered? I thought "enumerate" was the
way to do it, but maybe not in this case?

Ad ## 3 ## How does string replacement work in this
case? Why are the double backslashes needed? This
complicates things.


Could you help me with this? Any other, general
remarks?

Thanks in advance!

Albert-Jan

*******************.
** sample file
input program.
set seed = 12262007.
+  loop #i=1 to 100.
+     numeric n1 n2 n3 (n8.0).
+     compute f = abs(rnd(rv.normal(10,5))).
+     compute n1 = abs(rnd(rv.normal(10,5))).
+     compute n2 = abs(rnd(rv.normal(5,5))).
+     compute n3 = abs(rnd(rv.normal(0,5))).
+     end case.
+  end loop.
+ end file.
end input program.
exe.
save outfile = 'd:\temp\testit.sav'.

*******************.
** Actual program.

BEGIN PROGRAM.
import spss, os
def Num2String(file):
        """ Convert all numeric values of an SPSS sav
file to string
        and write entire file to num2string.xls. Handy
for e.g. disease codes
        because code '00001' would not be converted to
'1' by Excel. """
        try:
                # open file and build tuple of numeric
vars.
                spss.Submit("get file = %(myfile)s ."
%{'myfile' : file})
                numericvars=[ ]
                for i in
range(spss.GetVariableCount()):
                        if spss.GetVariableType(i) ==
0:

numericvars.append(spss.GetVariableName(i))
                for j in range(len(numericvars)):
                        k = numericvars[j]
                        # convert F vars to string.
                        if
spss.GetVariableFormat(j).find("F")==0:       ## 1 ##

                                spss.Submit(r"""
                                string temp (a10).
                                compute temp =
string(%(k)s,f8).
                                exe.
                                delete variables
%(k)s.
                                rename variables (temp
= %(k)s).
                                """ %locals())
                        # convert N vars to string.
                        elif
spss.GetVariableFormat(j).find("N")==0:
                                spss.Submit(r"""
                                string temp (a10).
                                compute temp =
string(%(k)s,n8).
                                exe.
                                delete variables
%(k)s.
                                rename variables (temp
= %(k)s).
                                """ %locals())
                # copy variable labels to 'stringed'
file and export to xls.
                spss.Submit("apply dictionary from
%(myfile)s / varinfo varlabel." %{'myfile' : file})
                spss.Submit(r"""save translate /
outfile = 'd:\temp\num2string.xls'
                / type = xls / version = 8 /
fieldnames / replace.""")
                print "The following numeric vars were
converted to string format: "
                for x, y  in
enumerate(range(len(numericvars))):
                        print y,
"\n".join(numericvars)  ## 2 ##

                        break
        # print something if file extension is not
sav, and if file or path does not exist.
        except:
                if  file[-4:-1] != 'sav':
                        print "File extension is " +
str.upper(file[-4:-1])
                        "\n This is probably not an
SPSS sav file."
                else:
                        if
os.path.exists('d:\\temp\\employee data.sav') ==
False:      ## 3 ##
                                print r"Input path
and/or file do not exist. Try again, dude."
# Num2String(r"'c:\program files\spss\employee
data.sav'")
Num2String(r"'d:\temp\testit.sav'")
END PROGRAM.




Cheers!
Albert-Jan

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Did you know that 87.166253% of all statistics claim a precision of results that is not justified by the method employed? [HELMUT RICHTER]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


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