This is the challenge as submitted to apply to the Code For America Fellowship

data_summary_census_tracts.py

import csv

def convert_to_lowercase(input_word):
    return input_word[0].lower() + input_word[1:]

def convert_to_python_style(input_word):
    return '_'.join(
        [
         convert_to_lowercase(individual_word)
         for individual_word
         in input_word.split(' ')
        ]
    )

def convert_to_human_readable(input_word):
    return " ".join(
        [individual_word.capitalize()
         for individual_word
         in input_word.split('_')
        ]
    )


class CensusTract(object):
    def __init__(self, **kwargs):
        for key, value in kwargs.iteritems():
            key = convert_to_python_style(key)
            if isinstance(value, basestring) and value.isdigit():
                value = int(value)
            self.__setattr__(key, value)

    @property
    def population_density(self):
        return float(self.population) / float(self.land_area)

    @property
    def housing_density(self):
        return float(self.housing_units) / float(self.land_area)

    def population_density_string(self):
        return "The population density of Census Tract {0} is {1} per square ?".format(self.name, self.population_density)    
    
    def housing_density_string(self):
        return "The population density of Census Tract {0} is {1} per square ?".format(self.name, self.housing_density)


class AllTracts(object):
    def __init__(self):
        self.tracts = []

    def add_tract(self, tract):
        self.tracts.append(tract)

    def order_tracts_by_key(self, lookup_key, reverse=False):
        if len(self.tracts) == 0:
            raise Exception('There are no tracts currently saved')
        elif not hasattr(self.tracts[0], lookup_key):
            raise Exception('The tract object does not have the key {0}'.format(lookup_key))
        return sorted(self.tracts, key=lambda x: getattr(x, lookup_key), reverse=reverse)

    def get_lowest_tract(self, lookup_key):
        return self.order_tracts_by_key(lookup_key)[0]

    def lowest_tract_string(self, lookup_key):
        tract = self.get_lowest_tract(lookup_key)
        attribute = convert_to_human_readable(lookup_key)
        return "The Lowest {0} Tract is {1} with a {0} of {2}".format(attribute, tract.name, getattr(tract, lookup_key))

    def get_highest_tract(self, lookup_key):
        return self.order_tracts_by_key(lookup_key)[-1]

    def highest_tract_string(self, lookup_key):
        tract = self.get_highest_tract(lookup_key)
        attribute = convert_to_human_readable(lookup_key)
        return "The Highest {0} Tract is {1} with a {0} of {2}".format(attribute, tract.name, getattr(tract, lookup_key))

    def print_tracts_by_key(self, lookup_key, reverse=False):
        for tract in self.order_tracts_by_key(lookup_key, reverse=reverse):
            if lookup_key == 'housing_density':
                print tract.housing_density_string()
            elif lookup_key == 'population_density':
                print tract.population_density_string()
            else:
                print getattr(tract, lookup_key)



with open('tracts.txt') as import_file:
    all_tracts = AllTracts()
    reader = csv.DictReader(import_file, delimiter='\t')
    for row in reader:
        all_tracts.add_tract(CensusTract(**row))


print "##############################"
print "ALL TRACTS BY POPULATION DENSITY"
all_tracts.print_tracts_by_key('population_density')
print "##############################"
print "##############################"
print "ALL TRACTS BY HOUSING DENSITY"
all_tracts.print_tracts_by_key('housing_density')
print "##############################"
print all_tracts.highest_tract_string('population_density')
print all_tracts.lowest_tract_string('population_density')
print "##############################"
print all_tracts.highest_tract_string('housing_density')
print all_tracts.lowest_tract_string('housing_density')
print "##############################"


# print "#convert_to_lowercase converts the first letter to lowercase"
# print convert_to_lowercase('Hello') == 'hello'

# print "#convert_to_lowercase converts only the first letter to lowercase"
# print convert_to_lowercase('HELLO') == 'hELLO'

# print "#convert_to_lowercase will not raise an error if it is already lowercase"
# print convert_to_lowercase('hello') == 'hello'

# print "#convert_to_python_style will work with a single word"
# print convert_to_python_style('Hello') == 'hello'

# print "#convert_to_python_style will downcase and link a 2 words divided by a space"
# print convert_to_python_style('Hello World') == 'hello_world'

# print "#convert_to_python_style will convert two separate styles"
# print convert_to_python_style('Hello world') == 'hello_world'