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item_14.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
numbers = [93, 86, 11, 68, 70]
a = sorted(numbers)#from a-z
print(a)
numbers.sort()
print(numbers)
# Example 2
class Tool:
def __init__(self, name, weight):#class to define name and weight var
self.name = name
self.weight = weight
## \!r gives repr representation of the object
def __repr__(self):#define a return value for calling class
return f"Tool1({self.name!r}, {self.weight})"
tools = [
Tool("level", 3.5),
Tool("hammer", 1.25),
Tool("screwdriver", 0.5),
Tool("chisel", 0.25),
]
print(tools)#by printing tools the content of list calls the class and repr om items
print(Tool("level", 3.5))
# Example 3
try:
tools.sort()#no direct sort possible on list with call of class/repr
except:
logging.exception("Expected")
else:
assert False
# Example 4
print("Unsorted:", repr(tools))
print(repr(tools.sort(key=lambda x: x.name)))#return is None but sorts the tools list
print("\nSorted: ", tools)
# Example 5
tools.sort(key=lambda x: x.weight)
print(tools.sort(key=lambda x: x.weight))#print statement a return None do tools will change order of list to weight sorted
print("By weight:", tools)
# Example 6
places = ["home", "work", "New York", "Paris"]
places.sort()#sort changes the list
print("Case sensitive: ", places)
places.sort(key=lambda x: x.lower())#the anon doesn't change type just sort order on lowercase
print("Case insensitive:", places)
# Example 7
power_tools = [
Tool("drill", 4),
Tool("circular saw", 5),
Tool("jackhammer", 40),
Tool("sander", 4),
]
# Example 8
# assert seems to check keys for evaluation
# if key same order then values order important
saw = (5, "circular saw") #change 5->6 then assertion error no compare first characters c < j
jackhammer = (5, "jackhammer")
assert not (jackhammer < saw) # Matches expectations
assert jackhammer > saw # Matches expectations j>c
# Example 9
drill = (4, "drill")
sander = (4, "sander")
print(drill[0])#takes first item of tuple
assert drill[0] == sander[0] # Same weight compare first items of tuples
assert drill[1] < sander[1] # Alphabetically less compare second items of tuple
assert drill < sander # Thus, drill comes first weigt are borh 4 so compare d<s
# Example 10
# sort first on weight then on name
power_tools.sort(key=lambda x: (x.weight, x.name))#calls tools class with repr
print(power_tools)#sort first on weight then on name
# Example 11
# sort first on weight then on name now reverse
power_tools.sort(
key=lambda x: (x.weight, x.name), reverse=True #reverse sort first on weight then on name
) # Makes all criteria descending
print(power_tools)
# Example 12
# first reverse sort on weight exept then normal sort on name
power_tools.sort(key=lambda x: (-x.weight, x.name))#see minus per sort option normal/reverse
print(power_tools)
# Example 13
# cannot use "-" with sort key and reverse option true
try:
power_tools.sort(key=lambda x: (x.weight, -x.name), reverse=True)#-x.name typeerror
# print(power_tools)
except:
logging.exception("Expected")
else:
assert False
try:
power_tools.sort(key=lambda x: (-x.weight, x.name), reverse=True)# double reverse on weight does work
print(power_tools)
except:
logging.exception("Expected")
else:
assert True
# Example 14
# prevent is theunary option else use 2 sort after each other
# firts sort name
power_tools.sort(key=lambda x: x.name) # Name ascending
print(power_tools)
power_tools.sort(key=lambda x: x.name, reverse=True) # Name ascending ans reverse on name
print(power_tools)
# then sort wiight
power_tools.sort(key=lambda x: x.weight, reverse=True) # Weight descending reverse on weight only
print(power_tools)
# Example 15
power_tools.sort(key=lambda x: x.name)#sort only on name
print(power_tools)
# Example 16
power_tools.sort(key=lambda x: x.weight, reverse=True)#sort only on weight
print(power_tools)