# 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
a = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h']
print('First four:', a[:4])
print('Last four: ', a[-4:])
print('Middle two:', a[3:-3])
First four: ['a', 'b', 'c', 'd'] Last four: ['e', 'f', 'g', 'h'] Middle two: ['d', 'e']
# Example 2
print (a[:5] == a[0:5])
True
# Example 3
print(a[5:] == a[5:len(a)])
True
# Example 4
print(a[:5])
print(a[:-1])
print(a[4:])
print(a[-3:])
print(a[2:5])
print(a[2:-1])
print(a[-3:-1])
['a', 'b', 'c', 'd', 'e'] ['a', 'b', 'c', 'd', 'e', 'f', 'g'] ['e', 'f', 'g', 'h'] ['f', 'g', 'h'] ['c', 'd', 'e'] ['c', 'd', 'e', 'f', 'g'] ['f', 'g']
# Example 5
a = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h']
print(a)
print(a[:]) # ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h']
print(a[:5]) # ['a', 'b', 'c', 'd', 'e']
print(a[:-1]) # ['a', 'b', 'c', 'd', 'e', 'f', 'g']
print(a[4:]) # ['e', 'f', 'g', 'h']
print(a[-3:]) # ['f', 'g', 'h']
print(a[2:5]) # ['c', 'd', 'e']
print(a[2:-1]) # ['c', 'd', 'e', 'f', 'g']
print(a[-3:-1]) # ['f', 'g']
['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'] ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'] ['a', 'b', 'c', 'd', 'e'] ['a', 'b', 'c', 'd', 'e', 'f', 'g'] ['e', 'f', 'g', 'h'] ['f', 'g', 'h'] ['c', 'd', 'e'] ['c', 'd', 'e', 'f', 'g'] ['f', 'g']
# Example 6
first_twenty_items = a[:20]
print(first_twenty_items)
last_twenty_items = a[-20:]
print(last_twenty_items)
['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'] ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h']
# Example 7
try:
print(a[200])
except:
logging.exception('Expected')
print("logged")
else:
assert(False)
logged
# Example 8
b = a[4:]
print('Before: ', b)
b[1] = 99
print('After: ', b)
print('No change:', a)
Before: ['e', 'f', 'g', 'h'] After: ['e', 99, 'g', 'h'] No change: ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h']
# Example 9
print('Before ', a)
a[2:7] = [99, 22, 14]
print('After ', a)
Before ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'] After ['a', 'b', 99, 22, 14, 'h']
# Example 10
b = a[:]
print (b == a and b is not a)
True
# Example 11
b = a
print('Before', a)
a[:] = [101, 102, 103]
assert a is b # Still the same list object
print('After ', a) # Now has different contents
Before ['a', 'b', 99, 22, 14, 'h'] After [101, 102, 103]