item_09.py

#!/usr/bin/env python3

# Copyright 2014 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.

# Preamble to mimick book environment
import logging
from pprint import pprint
from sys import stdout as STDOUT


# Example 1
import random
with open('my_file.txt', 'w') as f:
    for _ in range(10):
        f.write('a' * random.randint(0, 100))
        f.write('\n')

value = [len(x) for x in open('my_file.txt')]
print(value)


# Example 2
it = (len(x) for x in open('my_file.txt'))
print(it)


# Example 3
print(next(it))
print(next(it))


# Example 4
roots = ((x, x**0.5) for x in it)


# Example 5
print(next(roots))