You can use something like this to count the number of floating ips:

#!/usr/bin/python

import os
from quantumclient.quantum import client

def load_creds():
    d = {}
    d['username'] = os.environ['OS_USERNAME']
    d['password'] = os.environ['OS_PASSWORD']
    d['auth_url'] = os.environ['OS_AUTH_URL']
    d['tenant_name'] = os.environ['OS_TENANT_NAME']
    return d

qc = client.Client('2.0', **load_creds())
print len(qc.list_floatingips(fields=['id'])['floatingips'])

And you can filter by floating ip attributes if needed. e.g. qc.list_floatingips(fields=['id'], fixed_ip_address='')

Update: to show how the allocations can be totted up.

import os
import netaddr
from neutronclient.neutron import client

creds = {'username': os.environ['OS_USERNAME'],
         'password': os.environ['OS_PASSWORD'],
         'auth_url': os.environ['OS_AUTH_URL'],
         'tenant_name': os.environ['OS_TENANT_NAME']}

nc = client.Client('2.0', **creds)

all_nets = nc.list_networks()['networks']
ext_nets = [net for net in all_nets if net['router:external']]

total = 0
for net in ext_nets:
    net_total = 0
    # TODO request only the id and allocation_pools fields
    subnets = nc.list_subnets(network_id=net['id'])['subnets']
    for subnet in subnets:
        subnet_total = 0
        for alloc_pool in subnet['allocation_pools']:
            range = netaddr.IPRange(alloc_pool['start'], alloc_pool['end'])
            subnet_total += range.size
        net_total += subnet_total
        print 'net:', net['id'], 'subnet:', subnet['id'], 'count:', subnet_total
    total += net_total
    print 'net:', net['id'], 'count:', net_total

print 'total:', total