gistfile1.py

import csv

FIELDS = [
    "name", "timeZone_label", "utcOffset", "homepage", "governmentType_label", "isPartOf_label", "areaCode", "populationTotal",
    "elevation", "maximumElevation", "minimumElevation", "populationDensity", "wgs84_pos#lat", "wgs84_pos#long",
    "areaLand", "areaMetro", "areaUrban"
]

def audit_file(filename):
    with open(filename, 'rb') as fin:
        csvin = csv.DictReader(fin)
        col_types = {k:set() for k in csvin.fieldnames}
        missing = col_types.viewkeys() - FIELDS
        for row in csvin:
            for name, value in row.items():
                col_types[name].add(get_the_type(value))
        return col_types, missing


def get_the_type(value):
    if value in ('', 'NULL'):
        return None
    elif value.startswith('{'):
        return list
    for T in (int, float, str):
        try:
            return type(T(value))
        except ValueError:
            pass

col_types, missing = audit_file('/Users/stephan/Desktop/cities.csv')
print col_types, missing