6.7 Phone Number Cleaning and Standardisation

Cleaning and standardisation of phone numbers is done by a regular expression and rules based approach. Phone numbers can consist of a country code (possibly with an IDD - international direct dial - prefix), followed by an area code, then the actual number (with it's number of digits depending upon the country and sometimes even the area), and possibly an extension. The routines related to phone number standardisation are implemented in the phonenum.py module.

Assuming the input phone number is given in one string, the Febrl phone number standardiser parses this number into the five output fields shown in Table 6.3. The phone cleaning and parsing method has a list of all international country codes built in, as well as two routines to specifically parse Australian or Canadian/US phone numbers.

The following arguments need to be set when a phone number standardiser is initialised.

name
A name for the phone number standardiser. Most suitable is a short string.

description
A longer description of the standardiser. Note that this argument is not mandatory, the standardisation process works fine without a description.

input_fields
A string with a field name or a list of field names from the input data set, that will be standardised. If a list is given the field values will be concatenated into one string before the standardisation is done.

output_fields
A list of five field names as defined in the output data set. The phone number standardiser returns standardised phone numbers in the five output fields country code, country name, area code, number, and extension. It is possible to set fields to None if no output is to be written to a field (for example if one is not interested in the country code and name), as long as at least one output field is defined (i.e. not None).

default_country
This argument sets the default parsing approach to a certain country. Currently, it can either be set to 'australia' or 'canada/usa'. The default value is 'australia'.

The following example code shows how a phone number standardiser is initialised.

# ====================================================================

phone_std = PhoneNumStandardiser(name = 'Phone-Num-std',
                          description = 'Phone number standardiser',
                         input_fields = 'phone_num',
                        output_fields = ['phone_country_code',
                                         'phone_country_name',
                                         'phone_area_code',
                                         'phone_number',
                                         'phone_extension'],
                      default_country = 'australia')