python-deep-dive/First-Class_Functions/OperatorModule.py at master · maherme/python-deep-dive · GitHub

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#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Created on Mon Apr 26 20:27:45 2021

@author: maherme
"""
#%%

importoperator

dir(operator) # You can see the attributes typing this in the command line

#%%

res=operator.add(1, 2)
print(res)
res=operator.mul(2, 3)
print(res)
res=operator.truediv(3, 2)
print(res)
res=operator.floordiv(13, 2)
print(res)

#%%

fromfunctoolsimportreduce

res=reduce(lambdax, y: x*y, [1, 2, 3, 4])
print(res)

res=reduce(operator.mul, [1, 2, 3, 4])
print(res)

#%%

res=operator.lt(10, 3)
print(res)

#%%

fromoperatorimportis_

res=is_('abc', 'def')
print(res)
res=is_('abc', 'abc')
print(res)

#%%

res=operator.truth([])
print(res)
res=operator.truth([1])
print(res)

#%%

my_list= [1, 2, 3, 4]
res=operator.getitem(my_list, 1)
print(res)
operator.setitem(my_list, 1, 100)
print(my_list)
operator.delitem(my_list, 3)
print(my_list)

#%%

f=operator.itemgetter(2)
print(type(f)) # f is a callable

my_list= [1, 2, 3, 4]
res=f(my_list)
print(res)

#%%

f=operator.itemgetter(2, 3)
my_list= [1, 2, 3, 4]
res=f(my_list)
print(res)
res=f('python')
print(res)

#%%

classMyClass:
def__init__(self):
self.a=10
self.b=20
self.c=30

deftest(self):
print('test method running...')

obj=MyClass()

prop_a=operator.attrgetter('a') # Returns a callable.
res=prop_a(obj)
print(res)

my_var='b'
prop_b=operator.attrgetter(my_var)
res=prop_b(obj)
print(res)
my_var='c'
res=prop_b(obj) # Beware of prob_b continues looking for b.
print(res)

a, b, test=operator.attrgetter('a', 'b', 'test')(obj)
print(a, b, test)
test() # This calls the method.

#%%

f=lambdax: x.a
print(f(obj))

f=lambdax: (x[2], x[3])
x= [1, 2, 3, 4]
print(f(x))

#%%
# Let's look at sorting:

l= [5-10j, 3+3j, 2-100j]
res=sorted(l, key=lambdax: x.real)
print(res)

res=sorted(l, key=operator.attrgetter('real')) # You don't need to use lambda
print(res)

#%%

l= [(2, 3, 4), (1, 3, 5), (6,), (4, 100)]
res=sorted(l, key=lambdax: x[0])
print(res)

res=sorted(l, key=operator.itemgetter(0))
print(res)

#%%

classMyClass:
def__init__(self):
self.a=10
self.b=20

deftest(self, c):
print(self.a, self.b, c)

obj=MyClass()

print(obj.a, obj.b)
obj.test(100)

operator.methodcaller('test', 100)(obj) # You can call a method in this way

#%%

classMyClass:
def__init__(self):
self.a=10
self.b=20

deftest(self, c, d, *, e):
print(self.a, self.b, c, d, e)

obj=MyClass()

obj.test(100, 200, e=300)
operator.methodcaller('test', 100, 200, e=300)(obj)

f=operator.attrgetter('test')
f(obj)(100, 200, e=100)