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item_04.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 1
a = 0b10111011
b = 0xc5f
print('Binary is %d, hex is %d' % (a, b))
# Example 2
key = 'my_var'
value = 1.234
formatted = '%-10s = %.2f' % (key, value)
print(formatted)
# Example 3
try:
reordered_tuple = '%-10s = %.2f' % (value, key)
except:
logging.exception('Expected')
else:
assert False
# Example 4
try:
reordered_string = '%.2f = %-10s' % (key, value)
except:
logging.exception('Expected')
else:
assert False
# Example 5
pantry = [
('avocados', 1.25),
('bananas', 2.5),
('cherries', 15),
]
for i, (item, count) in enumerate(pantry):
print('#%d: %-10s = %.2f' % (i, item, count))
# Example 6
for i, (item, count) in enumerate(pantry):
print('#%d: %-10s = %d' % (
i + 1,
item.title(),
round(count)))
# Example 7
template = '%s loves food. See %s cook.'
name = 'Max'
formatted = template % (name, name)
print(formatted)
# Example 8
name = 'brad'
formatted = template % (name.title(), name.title())
print(formatted)
# Example 9
key = 'my_var'
value = 1.234
old_way = '%-10s = %.2f' % (key, value)
new_way = '%(key)-10s = %(value).2f' % {
'key': key, 'value': value} # Original
reordered = '%(key)-10s = %(value).2f' % {
'value': value, 'key': key} # Swapped
assert old_way == new_way == reordered
# Example 10
name = 'Max'
template = '%s loves food. See %s cook.'
before = template % (name, name) # Tuple
template = '%(name)s loves food. See %(name)s cook.'
after = template % {'name': name} # Dictionary
assert before == after
# Example 11
for i, (item, count) in enumerate(pantry):
before = '#%d: %-10s = %d' % (
i + 1,
item.title(),
round(count))
after = '#%(loop)d: %(item)-10s = %(count)d' % {
'loop': i + 1,
'item': item.title(),
'count': round(count),
}
assert before == after
# Example 12
soup = 'lentil'
formatted = 'Today\'s soup is %(soup)s.' % {'soup': soup}
print(formatted)
# Example 13
menu = {
'soup': 'lentil',
'oyster': 'kumamoto',
'special': 'schnitzel',
}
template = ('Today\'s soup is %(soup)s, '
'buy one get two %(oyster)s oysters, '
'and our special entrée is %(special)s.')
formatted = template % menu
print(formatted)
# Example 14
a = 1234.5678
formatted = format(a, ',.2f')
print(formatted)
b = 'my string'
formatted = format(b, '^20s')
print('*', formatted, '*')
# Example 15
key = 'my_var'
value = 1.234
formatted = '{} = {}'.format(key, value)
print(formatted)
# Example 16
formatted = '{:<10} = {:.2f}'.format(key, value)
print(formatted)
# Example 17
print('%.2f%%' % 12.5)
print('{} replaces {{}}'.format(1.23))
# Example 18
formatted = '{1} = {0}'.format(key, value)
print(formatted)
# Example 19
formatted = '{0} loves food. See {0} cook.'.format(name)
print(formatted)
# Example 20
for i, (item, count) in enumerate(pantry):
old_style = '#%d: %-10s = %d' % (
i + 1,
item.title(),
round(count))
new_style = '#{}: {:<10s} = {}'.format(
i + 1,
item.title(),
round(count))
assert old_style == new_style
# Example 21
formatted = 'First letter is {menu[oyster][0]!r}'.format(
menu=menu)
print(formatted)
# Example 22
old_template = (
'Today\'s soup is %(soup)s, '
'buy one get two %(oyster)s oysters, '
'and our special entrée is %(special)s.')
old_formatted = template % {
'soup': 'lentil',
'oyster': 'kumamoto',
'special': 'schnitzel',
}
new_template = (
'Today\'s soup is {soup}, '
'buy one get two {oyster} oysters, '
'and our special entrée is {special}.')
new_formatted = new_template.format(
soup='lentil',
oyster='kumamoto',
special='schnitzel',
)
assert old_formatted == new_formatted
# Example 23
key = 'my_var'
value = 1.234
formatted = f'{key} = {value}'
print(formatted)
# Example 24
formatted = f'{key!r:<10} = {value:.2f}'
print(formatted)
# Example 25
f_string = f'{key:<10} = {value:.2f}'
c_tuple = '%-10s = %.2f' % (key, value)
str_args = '{:<10} = {:.2f}'.format(key, value)
str_kw = '{key:<10} = {value:.2f}'.format(key=key, value=value)
c_dict = '%(key)-10s = %(value).2f' % {'key': key, 'value': value}
assert c_tuple == c_dict == f_string
assert str_args == str_kw == f_string
# Example 26
for i, (item, count) in enumerate(pantry):
old_style = '#%d: %-10s = %d' % (
i + 1,
item.title(),
round(count))
new_style = '#{}: {:<10s} = {}'.format(
i + 1,
item.title(),
round(count))
f_string = f'#{i+1}: {item.title():<10s} = {round(count)}'
assert old_style == new_style == f_string
# Example 27
for i, (item, count) in enumerate(pantry):
print(f'#{i+1}: '
f'{item.title():<10s} = '
f'{round(count)}')
# Example 28
places = 3
number = 1.23456
print(f'My number is {number:.{places}f}')