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item_15.py
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#!/usr/bin/env PYTHONHASHSEED=1234 python3
# Copyright 2014-2019 Brett Slatkin, Pearson Education Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# Reproduce book environment
import random
random.seed(1234)
import logging
from pprint import pprint
from sys import stdout as STDOUT
# Write all output to a temporary directory
import atexit
import gc
import io
import os
import tempfile
TEST_DIR = tempfile.TemporaryDirectory()
atexit.register(TEST_DIR.cleanup)
# Make sure Windows processes exit cleanly
OLD_CWD = os.getcwd()
atexit.register(lambda: os.chdir(OLD_CWD))
os.chdir(TEST_DIR.name)
def close_open_files():
everything = gc.get_objects()
for obj in everything:
if isinstance(obj, io.IOBase):
obj.close()
atexit.register(close_open_files)
# Example 2
baby_names = {
'cat': 'kitten',
'dog': 'puppy',
}
print(baby_names)
# Example 4
print(list(baby_names.keys()))
print(list(baby_names.values()))
print(list(baby_names.items()))
print(baby_names.popitem()) # Last item inserted
# Example 6
def my_func(**kwargs):
for key, value in kwargs.items():
print(f'{key} = {value}')
my_func(goose='gosling', kangaroo='joey')
# Example 8
class MyClass:
def __init__(self):
self.alligator = 'hatchling'
self.elephant = 'calf'
a = MyClass()
for key, value in a.__dict__.items():
print(f'{key} = {value}')
# Example 9
votes = {
'otter': 1281,
'polar bear': 587,
'fox': 863,
}
# Example 10
def populate_ranks(votes, ranks):
names = list(votes.keys())
names.sort(key=votes.get, reverse=True)
for i, name in enumerate(names, 1):
ranks[name] = i
# Example 11
def get_winner(ranks):
return next(iter(ranks))
# Example 12
ranks = {}
populate_ranks(votes, ranks)
print(ranks)
winner = get_winner(ranks)
print(winner)
# Example 13
from collections.abc import MutableMapping
class SortedDict(MutableMapping):
def __init__(self):
self.data = {}
def __getitem__(self, key):
return self.data[key]
def __setitem__(self, key, value):
self.data[key] = value
def __delitem__(self, key):
del self.data[key]
def __iter__(self):
keys = list(self.data.keys())
#keys.sort()#kan probleem
for key in keys:
yield key
def __len__(self):
return len(self.data)
my_dict = SortedDict()
my_dict['otter'] = 1 #assign value to dict
my_dict['cheeta'] = 2
my_dict['anteater'] = 3
my_dict['deer'] = 4
print(my_dict['otter'])
assert my_dict['otter'] == 1
assert 'cheeta' in my_dict
del my_dict['cheeta']
assert 'cheeta' not in my_dict #by de l method in class remove key
expected = [('anteater', 3), ('deer', 4), ('otter', 1)]
a= list(my_dict.items())
a.sort()
print(a)
assert a == expected #list as to be the same sort sequence
assert list(my_dict.items()) == expected #assertion error not sorted against sorted
assert not isinstance(my_dict, dict)
print(isinstance(my_dict,dict))#false so my_dict is not a dict type
# Example 14
sorted_ranks = SortedDict()
populate_ranks(votes, sorted_ranks)
print(sorted_ranks.data)
winner = get_winner(sorted_ranks)
print(winner)
# Example 15
def get_winner(ranks):
for name, rank in ranks.items():#take item with rank 1 out of dict
if rank == 1:
return name
winner = get_winner(sorted_ranks)#or get item through special class
print(winner)
# Example 16
try:
def get_winner(ranks):
if not isinstance(ranks, dict):#test for ranks == dict returns error
raise TypeError('must provide a dict instance')
return next(iter(ranks))
assert get_winner(ranks) == 'otter'
get_winner(sorted_ranks)
except:
logging.exception('Expected')
else:
assert False