Iterating CSV file with auto-field-type-conversion (requires field_converter.py) and click.progressbar...

csv_iterator.py

import sys
import csv
import click
from field_converter import FieldConverter

class CSV_Iterator:
    def __init__(self, path, skip_header=False, with_progress_bar=False,
                 field_converter=None):
        self.path = path
        self.with_progress_bar = with_progress_bar
        self.field_converter = field_converter

        self.f = open(path, 'r')
        self.line_count = sum(1 for line in self.f)

        self.f.seek(0)  # rewind
        self.r = csv.reader(self.f, dialect='excel')
        if skip_header:
            self.r.next()
            self.line_count -= 1

        print '(%d lines)' % (self.line_count,)

        if self.with_progress_bar:
            self.bar = click.progressbar(self.r, self.line_count)

    def __iter__(self):
        return self

    def next(self):
        try:
            if self.with_progress_bar:
                fields = self.bar.next()
            else:
                fields = self.r.next()
            if self.field_converter:
                try:
                    fields = self.field_converter.convert(fields)
                except:
                    print sys.exc_info()
            return fields
        except:
            raise StopIteration

    def __enter__(self):
        return self

    def __exit__(self, exc_type, exc_value, traceback):
        if exc_type:
            return False
        if self.with_progress_bar:
            print
        self.f.close()
        return True



"""
# usage
from csv_iterator import CSV_Iterator

def foobar(csv_path):
    with CSV_Iterator(csv_path,
                  skip_header=True,
                  with_progress_bar=True,
                  field_converter=FieldConverter(int, int, 'iso-8859-1', 'iso-8859-1', float)) as line:
        for id, uid, title, query, target in line:
            ...
"""