Purpose:
To provide a simple function that maps the raw IPUMS data extract to the variable values it represents.

For example, the first few lines of an IPUMS data file might look like the following:

2008010000008200082000
2008010000002300066000
2008010000008800070021
2008010000006600070000
2008010000006600069000

Here, each line represents a single survey respondent. The first four characters of the line are the YEAR variable, the next two are the STATEFIP variable, the next 10 are the PERWT, etc.

The row_generator() function uses the IPUMS data file and the DDI xml file that accompanies it to automatically parse each line of the data file into a dictionary with each key representing the variable value.

Usage:

Step 1: Download the IPUMS dat file (ie, "usa_00001.dat") and the corresponding DDI file (for example, "usa_00001.xml") from the IPUMS website.
Step 2: Import the row_generator function from the ipums_lib function
Step 3: Create a row_generator, supplying the paths to the IPUMS dat file and the corresponding DDI file.

Example Usage:
>>> from ipums_lib import row_generator
>>>
>>> rows = row_generator(datapath = "usa_00001.dat", ddipath = "usa_00001.xml")
>>> for row in rows:
>>>     print row

{u'STATEFIP': '01', u'PERWT': '00000082.00', u'AGE': '082', u'MIGPLAC1': '000', u'YEAR': '2008'}
{u'STATEFIP': '01', u'PERWT': '00000023.00', u'AGE': '066', u'MIGPLAC1': '000', u'YEAR': '2008'}
{u'STATEFIP': '01', u'PERWT': '00000088.00', u'AGE': '070', u'MIGPLAC1': '021', u'YEAR': '2008'}
{u'STATEFIP': '01', u'PERWT': '00000066.00', u'AGE': '070', u'MIGPLAC1': '000', u'YEAR': '2008'}
{u'STATEFIP': '01', u'PERWT': '00000066.00', u'AGE': '069', u'MIGPLAC1': '000', u'YEAR': '2008'}