LinuxerHAN: 06/07/2020

** Itertools Module : Iterator Functions for Efficient Looping

==========================================

import itertools

counter = itertools.count()

for num in counter:

print(num)

---------------------------------

... 정지 명령을 내릴때 까지 계속 1씩 증가

==========================================

import itertools

counter = itertools.count()

print(next(counter))

---------------------------------

import itertools

counter = itertools.count()

print(next(counter))

---------------------------------

==========================================

import itertools

counter = itertools.count()

data = [100, 200, 300, 400]

daily_data = list(zip(itertools.count(), data))

print(daily_data)

---------------------------------

[(0, 100), (1, 200), (2, 300), (3, 400)]

==========================================

import itertools

counter = itertools.count(start=5)

print(next(counter))

---------------------------------

import itertools

counter = itertools.count(start=5, step=5)

print(next(counter))

---------------------------------

import itertools

counter = itertools.count(start=5, step=-2.5)

print(next(counter))

---------------------------------

2.5

0.0

-2.5

==========================================

import itertools

data = [100, 200, 300, 400]

daily_data = list(zip(range(10), data))

print(daily_data)

---------------------------------

[(0, 100), (1, 200), (2, 300), (3, 400)]

---------------------------------

import itertools

data = [100, 200, 300, 400]

daily_data = list(itertools.zip_longest(range(10), data))

print(daily_data)

---------------------------------

[(0, 100), (1, 200), (2, 300), (3, 400), (4, None), (5, None), (6, None), (7,

None), (8, None), (9, None)]

==========================================

import itertools

counter = itertools.cycle([1, 2, 3])

print(next(counter))

---------------------------------

import itertools

counter = itertools.cycle(('On', 'Off'))

print(next(counter))

---------------------------------

Off

---------------------------------

import itertools

counter = itertools.repeat(2, times=3)

print(next(counter))

---------------------------------

2Traceback (most recent call last):

File "C:\Users\purunet\Documents\py9\ii.py", line 9, in <module>

print(next(counter))

StopIteration

==========================================

import itertools

counter = itertools.repeat(2, times=3)

squares = map(pow, range(10), itertools.repeat(2))

print(list(squares))

---------------------------------

[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]

---------------------------------

import itertools

counter = itertools.repeat(2, times=3)

squares = itertools.starmap(pow, [(0, 2), (1, 2), (2, 2)])

print(list(squares))

---------------------------------

[0, 1, 4]

==========================================

import itertools

letters = ['a', 'b', 'c', 'd']

numbers = [0, 1, 2, 3]

names = ['LinuxerHAN', 'SeokDu']

result = itertools.combinations(letters, 2)

for item in result:

print(item)

---------------------------------

('a', 'b')

('a', 'c')

('a', 'd')

('b', 'c')

('b', 'd')

('c', 'd')

---------------------------------

import itertools

letters = ['a', 'b', 'c', 'd']

numbers = [0, 1, 2, 3]

names = ['LinuxerHAN', 'SeokDu']

result = itertools.permutations(letters, 2)

for item in result:

print(item)

---------------------------------

('a', 'b')

('a', 'c')

('a', 'd')

('b', 'a')

('b', 'c')

('b', 'd')

('c', 'a')

('c', 'b')

('c', 'd')

('d', 'a')

('d', 'b')

('d', 'c')

---------------------------------

import itertools

letters = ['a', 'b', 'c', 'd']

numbers = [0, 1, 2, 3]

names = ['LinuxerHAN', 'SeokDu']

result = itertools.product(numbers, repeat=4)

for item in result:

print(item)

---------------------------------

(0, 0, 0, 0)

(0, 0, 0, 1)

(0, 0, 0, 2)

(0, 0, 0, 3)

(0, 0, 1, 0)

(0, 0, 1, 1)

(0, 0, 1, 2)

(0, 0, 1, 3)

(0, 0, 2, 0)

(0, 0, 2, 1)

(0, 0, 2, 2)

(0, 0, 2, 3)

(0, 0, 3, 0)

(0, 0, 3, 1)

(0, 0, 3, 2)

(0, 0, 3, 3)

(0, 1, 0, 0)

(0, 1, 0, 1)

(0, 1, 0, 2)

(0, 1, 0, 3)

(0, 1, 1, 0)

(0, 1, 1, 1)

(0, 1, 1, 2)

(0, 1, 1, 3)

(0, 1, 2, 0)

(0, 1, 2, 1)

(0, 1, 2, 2)

(0, 1, 2, 3)

(0, 1, 3, 0)

(0, 1, 3, 1)

(0, 1, 3, 2)

(0, 1, 3, 3)

(0, 2, 0, 0)

(0, 2, 0, 1)

(0, 2, 0, 2)

(0, 2, 0, 3)

(0, 2, 1, 0)

(0, 2, 1, 1)

(0, 2, 1, 2)

(0, 2, 1, 3)

(0, 2, 2, 0)

(0, 2, 2, 1)

(0, 2, 2, 2)

(0, 2, 2, 3)

(0, 2, 3, 0)

(0, 2, 3, 1)

(0, 2, 3, 2)

(0, 2, 3, 3)

(0, 3, 0, 0)

(0, 3, 0, 1)

(0, 3, 0, 2)

(0, 3, 0, 3)

(0, 3, 1, 0)

(0, 3, 1, 1)

(0, 3, 1, 2)

(0, 3, 1, 3)

(0, 3, 2, 0)

(0, 3, 2, 1)

(0, 3, 2, 2)

(0, 3, 2, 3)

(0, 3, 3, 0)

(0, 3, 3, 1)

(0, 3, 3, 2)

(0, 3, 3, 3)

(1, 0, 0, 0)

(1, 0, 0, 1)

(1, 0, 0, 2)

(1, 0, 0, 3)

(1, 0, 1, 0)

(1, 0, 1, 1)

(1, 0, 1, 2)

(1, 0, 1, 3)

(1, 0, 2, 0)

(1, 0, 2, 1)

(1, 0, 2, 2)

(1, 0, 2, 3)

(1, 0, 3, 0)

(1, 0, 3, 1)

(1, 0, 3, 2)

(1, 0, 3, 3)

(1, 1, 0, 0)

(1, 1, 0, 1)

(1, 1, 0, 2)

(1, 1, 0, 3)

(1, 1, 1, 0)

(1, 1, 1, 1)

(1, 1, 1, 2)

(1, 1, 1, 3)

(1, 1, 2, 0)

(1, 1, 2, 1)

(1, 1, 2, 2)

(1, 1, 2, 3)

(1, 1, 3, 0)

(1, 1, 3, 1)

(1, 1, 3, 2)

(1, 1, 3, 3)

(1, 2, 0, 0)

(1, 2, 0, 1)

(1, 2, 0, 2)

(1, 2, 0, 3)

(1, 2, 1, 0)

(1, 2, 1, 1)

(1, 2, 1, 2)

(1, 2, 1, 3)

(1, 2, 2, 0)

(1, 2, 2, 1)

(1, 2, 2, 2)

(1, 2, 2, 3)

(1, 2, 3, 0)

(1, 2, 3, 1)

(1, 2, 3, 2)

(1, 2, 3, 3)

(1, 3, 0, 0)

(1, 3, 0, 1)

(1, 3, 0, 2)

(1, 3, 0, 3)

(1, 3, 1, 0)

(1, 3, 1, 1)

(1, 3, 1, 2)

(1, 3, 1, 3)

(1, 3, 2, 0)

(1, 3, 2, 1)

(1, 3, 2, 2)

(1, 3, 2, 3)

(1, 3, 3, 0)

(1, 3, 3, 1)

(1, 3, 3, 2)

(1, 3, 3, 3)

(2, 0, 0, 0)

(2, 0, 0, 1)

(2, 0, 0, 2)

(2, 0, 0, 3)

(2, 0, 1, 0)

(2, 0, 1, 1)

(2, 0, 1, 2)

(2, 0, 1, 3)

(2, 0, 2, 0)

(2, 0, 2, 1)

(2, 0, 2, 2)

(2, 0, 2, 3)

(2, 0, 3, 0)

(2, 0, 3, 1)

(2, 0, 3, 2)

(2, 0, 3, 3)

(2, 1, 0, 0)

(2, 1, 0, 1)

(2, 1, 0, 2)

(2, 1, 0, 3)

(2, 1, 1, 0)

(2, 1, 1, 1)

(2, 1, 1, 2)

(2, 1, 1, 3)

(2, 1, 2, 0)

(2, 1, 2, 1)

(2, 1, 2, 2)

(2, 1, 2, 3)

(2, 1, 3, 0)

(2, 1, 3, 1)

(2, 1, 3, 2)

(2, 1, 3, 3)

(2, 2, 0, 0)

(2, 2, 0, 1)

(2, 2, 0, 2)

(2, 2, 0, 3)

(2, 2, 1, 0)

(2, 2, 1, 1)

(2, 2, 1, 2)

(2, 2, 1, 3)

(2, 2, 2, 0)

(2, 2, 2, 1)

(2, 2, 2, 2)

(2, 2, 2, 3)

(2, 2, 3, 0)

(2, 2, 3, 1)

(2, 2, 3, 2)

(2, 2, 3, 3)

(2, 3, 0, 0)

(2, 3, 0, 1)

(2, 3, 0, 2)

(2, 3, 0, 3)

(2, 3, 1, 0)

(2, 3, 1, 1)

(2, 3, 1, 2)

(2, 3, 1, 3)

(2, 3, 2, 0)

(2, 3, 2, 1)

(2, 3, 2, 2)

(2, 3, 2, 3)

(2, 3, 3, 0)

(2, 3, 3, 1)

(2, 3, 3, 2)

(2, 3, 3, 3)

(3, 0, 0, 0)

(3, 0, 0, 1)

(3, 0, 0, 2)

(3, 0, 0, 3)

(3, 0, 1, 0)

(3, 0, 1, 1)

(3, 0, 1, 2)

(3, 0, 1, 3)

(3, 0, 2, 0)

(3, 0, 2, 1)

(3, 0, 2, 2)

(3, 0, 2, 3)

(3, 0, 3, 0)

(3, 0, 3, 1)

(3, 0, 3, 2)

(3, 0, 3, 3)

(3, 1, 0, 0)

(3, 1, 0, 1)

(3, 1, 0, 2)

(3, 1, 0, 3)

(3, 1, 1, 0)

(3, 1, 1, 1)

(3, 1, 1, 2)

(3, 1, 1, 3)

(3, 1, 2, 0)

(3, 1, 2, 1)

(3, 1, 2, 2)

(3, 1, 2, 3)

(3, 1, 3, 0)

(3, 1, 3, 1)

(3, 1, 3, 2)

(3, 1, 3, 3)

(3, 2, 0, 0)

(3, 2, 0, 1)

(3, 2, 0, 2)

(3, 2, 0, 3)

(3, 2, 1, 0)

(3, 2, 1, 1)

(3, 2, 1, 2)

(3, 2, 1, 3)

(3, 2, 2, 0)

(3, 2, 2, 1)

(3, 2, 2, 2)

(3, 2, 2, 3)

(3, 2, 3, 0)

(3, 2, 3, 1)

(3, 2, 3, 2)

(3, 2, 3, 3)

(3, 3, 0, 0)

(3, 3, 0, 1)

(3, 3, 0, 2)

(3, 3, 0, 3)

(3, 3, 1, 0)

(3, 3, 1, 1)

(3, 3, 1, 2)

(3, 3, 1, 3)

(3, 3, 2, 0)

(3, 3, 2, 1)

(3, 3, 2, 2)

(3, 3, 2, 3)

(3, 3, 3, 0)

(3, 3, 3, 1)

(3, 3, 3, 2)

(3, 3, 3, 3)

---------------------------------

import itertools

letters = ['a', 'b', 'c', 'd']

numbers = [0, 1, 2, 3]

names = ['LinuxerHAN', 'SeokDu']

result = itertools.combinations_with_replacement(numbers, 4)

for item in result:

print(item)

---------------------------------

(0, 0, 0, 0)

(0, 0, 0, 1)

(0, 0, 0, 2)

(0, 0, 0, 3)

(0, 0, 1, 1)

(0, 0, 1, 2)

(0, 0, 1, 3)

(0, 0, 2, 2)

(0, 0, 2, 3)

(0, 0, 3, 3)

(0, 1, 1, 1)

(0, 1, 1, 2)

(0, 1, 1, 3)

(0, 1, 2, 2)

(0, 1, 2, 3)

(0, 1, 3, 3)

(0, 2, 2, 2)

(0, 2, 2, 3)

(0, 2, 3, 3)

(0, 3, 3, 3)

(1, 1, 1, 1)

(1, 1, 1, 2)

(1, 1, 1, 3)

(1, 1, 2, 2)

(1, 1, 2, 3)

(1, 1, 3, 3)

(1, 2, 2, 2)

(1, 2, 2, 3)

(1, 2, 3, 3)

(1, 3, 3, 3)

(2, 2, 2, 2)

(2, 2, 2, 3)

(2, 2, 3, 3)

(2, 3, 3, 3)

(3, 3, 3, 3)

==========================================

import itertools

letters = ['a', 'b', 'c', 'd']

numbers = [0, 1, 2, 3]

names = ['LinuxerHAN', 'SeokDu']

combined = itertools.chain(letters, numbers, names)

for item in combined:

print(item

---------------------------------

LinuxerHAN

SeokDu

==========================================

import itertools

letters = ['a', 'b', 'c', 'd']

numbers = [0, 1, 2, 3]

names = ['LinuxerHAN', 'SeokDu']

result = itertools.islice(range(10), 5)

for item in result:

print(item)

---------------------------------

import itertools

letters = ['a', 'b', 'c', 'd']

numbers = [0, 1, 2, 3]

names = ['LinuxerHAN', 'SeokDu']

result = itertools.islice(range(10), 1, 5)

for item in result:

print(item)

---------------------------------

import itertools

letters = ['a', 'b', 'c', 'd']

numbers = [0, 1, 2, 3]

names = ['LinuxerHAN', 'SeokDu']

result = itertools.islice(range(10), 1, 5, 2)

for item in result:

print(item)

---------------------------------

==========================================

import itertools

with open('test.log', 'r') as f:

header = itertools.islice(f, 3)

for line in header:

print(line)

---------test.log-------------------

Date: 2020-06-07

Author: LinuxerHAN

Description: This is a sample log file

Okay, so this is a sample entry.

I'm going to write a few more lines here.

For the sake of this video, let's pretend this log file is thousands

and thousands of lines... okay?

---------------------------------

Date: 2020-06-07

Author: LinuxerHAN

Description: This is a sample log file

---------------------------------

import itertools

with open('test.log', 'r') as f:

header = itertools.islice(f, 3)

for line in header:

print(line)

---------test.log-------------------

Date: 2020-06-07

Author: LinuxerHAN

Description: This is a sample log file

Okay, so this is a sample entry.

I'm going to write a few more lines here.

For the sake of this video, let's pretend this log file is thousands

and thousands of lines... okay?

---------------------------------

Date: 2020-06-07

Author: LinuxerHAN

Description: This is a sample log file

---------------------------------

import itertools

with open('test.log', 'r') as f:

header = itertools.islice(f, 3)

for line in header:

print(line, end='')

---------test.log-------------------

Date: 2020-06-07

Author: LinuxerHAN

Description: This is a sample log file

Okay, so this is a sample entry.

I'm going to write a few more lines here.

For the sake of this video, let's pretend this log file is thousands

and thousands of lines... okay?

---------------------------------

Date: 2020-06-07

Author: LinuxerHAN

Description: This is a sample log file

==========================================

import itertools

letters = ['a', 'b', 'c', 'd']

numbers = [0, 1, 2, 3]

names = ['LinuxerHAN', 'SeokDu']

selectors = [True, True, False, True]

result = itertools.compress(letters, selectors)

for item in result:

print(item)

---------------------------------

==========================================

import itertools

def lt_2(n):

if n < 2:

return True

return False

letters = ['a', 'b', 'c', 'd']

numbers = [0, 1, 2, 3]

names = ['LinuxerHAN', 'SeokDu']

selectors = [True, True, False, True]

result = filter(lt_2, numbers)

for item in result:

print(item)

---------------------------------

import itertools

def lt_2(n):

if n < 2:

return True

return False

letters = ['a', 'b', 'c', 'd']

numbers = [0, 1, 2, 3]

names = ['LinuxerHAN', 'SeokDu']

selectors = [True, True, False, True]

result = itertools.filterfalse(lt_2, numbers)

for item in result:

print(item)

---------------------------------

import itertools

def lt_2(n):

if n < 2:

return True

return False

letters = ['a', 'b', 'c', 'd']

numbers = [0, 1, 2, 3, 2, 1, 0]

names = ['LinuxerHAN', 'SeokDu']

selectors = [True, True, False, True]

result = itertools.filterfalse(lt_2, numbers)

for item in result:

print(item)

---------------------------------

import itertools

def lt_2(n):

if n < 2:

return True

return False

letters = ['a', 'b', 'c', 'd']

numbers = [0, 1, 2, 3, 2, 1, 0]

names = ['LinuxerHAN', 'SeokDu']

selectors = [True, True, False, True]

result = itertools.dropwhile(lt_2, numbers)

for item in result:

print(item)

---------------------------------

import itertools

def lt_2(n):

if n < 2:

return True

return False

letters = ['a', 'b', 'c', 'd']

numbers = [0, 1, 2, 3, 2, 1, 0]

names = ['LinuxerHAN', 'SeokDu']

selectors = [True, True, False, True]

result = itertools.takewhile(lt_2, numbers)

for item in result:

print(item)

---------------------------------

==========================================

import itertools

letters = ['a', 'b', 'c', 'd']

numbers = [0, 1, 2, 3, 2, 1, 0]

names = ['LinuxerHAN', 'SeokDu']

result = itertools.accumulate(numbers)

for item in result:

print(item)

---------------------------------

import itertools

import operator

letters = ['a', 'b', 'c', 'd']

numbers = [1, 2, 3, 2, 1, 0]

names = ['LinuxerHAN', 'SeokDu']

result = itertools.accumulate(numbers, operator.mul)

for item in result:

print(item)

---------------------------------

==========================================

import itertools

def get_state(person):

return person['state']

people = [

{

'name': 'Linuxer HAN',

'city': 'Gotham',

'state': 'NY'

{

'name': 'SeokDu HAN',

'city': 'Kings Landing',

'state': 'NY'

{

'name': 'Corey Schafer',

'city': 'Boulder',

'state': 'CO'

{

'name': 'Al Einstein',

'city': 'Denver',

'state': 'CO'

{

'name': 'John Henry',

'city': 'Hinton',

'state': 'WV'

{

'name': 'Randy Moss',

'city': 'Rand',

'state': 'WV'

{

'name': 'Nicole K',

'city': 'Asheville',

'state': 'NC'

{

'name': 'Jim Doe',

'city': 'Charlotte',

'state': 'NC'

{

'name': 'Jane Taylor',

'city': 'Faketown',

'state': 'NC'

}

]

person_group = itertools.groupby(people, get_state)

for key, group in person_group:

print(key)

for person in group:

print(person)

print()

---------------------------------

{'name': 'Linuxer HAN', 'city': 'Gotham', 'state': 'NY'}

{'name': 'SeokDu HAN', 'city': 'Kings Landing', 'state': 'NY'}

{'name': 'Corey Schafer', 'city': 'Boulder', 'state': 'CO'}

{'name': 'Al Einstein', 'city': 'Denver', 'state': 'CO'}

{'name': 'John Henry', 'city': 'Hinton', 'state': 'WV'}

{'name': 'Randy Moss', 'city': 'Rand', 'state': 'WV'}

{'name': 'Nicole K', 'city': 'Asheville', 'state': 'NC'}

{'name': 'Jim Doe', 'city': 'Charlotte', 'state': 'NC'}

{'name': 'Jane Taylor', 'city': 'Faketown', 'state': 'NC'}

---------------------------------

import itertools

def get_state(person):

return person['state']

people = [

{

'name': 'Linuxer HAN',

'city': 'Gotham',

'state': 'NY'

{

'name': 'SeokDu HAN',

'city': 'Kings Landing',

'state': 'NY'

{

'name': 'Corey Schafer',

'city': 'Boulder',

'state': 'CO'

{

'name': 'Al Einstein',

'city': 'Denver',

'state': 'CO'

{

'name': 'John Henry',

'city': 'Hinton',

'state': 'WV'

{

'name': 'Randy Moss',

'city': 'Rand',

'state': 'WV'

{

'name': 'Nicole K',

'city': 'Asheville',

'state': 'NC'

{

'name': 'Jim Doe',

'city': 'Charlotte',

'state': 'NC'

{

'name': 'Jane Taylor',

'city': 'Faketown',

'state': 'NC'

}

]

person_group = itertools.groupby(people, get_state)

for key, group in person_group:

print(key, len(list(group)))

---------------------------------

NY 2

CO 2

WV 2

NC 3

==========================================

** Coding Problem: Creating Your Own Iterators

==========================================

my_sentence = Sentence('This is a test')

for word in my_sentence:
print(word)

# This should have the following output:
# This
# is
# a
# test

---------------------------------

class Sentence:

def __init__(self, sentence):
self.sentence = sentence
self.index = 0
self.words = self.sentence.split()

def __iter__(self):
return self

def __next__(self):
if self.index >= len(self.words):
raise StopIteration
index = self.index
self.index += 1
return self.words[index]

my_sentence = Sentence('This is a test')

for word in my_sentence:
print(word)

---------------------------------

This
is
a
test

==========================================
==========================================

class Sentence:

def __init__(self, sentence):
self.sentence = sentence
self.index = 0
self.words = self.sentence.split()

def __iter__(self):
return self

def __next__(self):
if self.index >= len(self.words):
raise StopIteration
index = self.index
self.index += 1
return self.words[index]

my_sentence = Sentence('This is a test')

print(next(my_sentence))
print(next(my_sentence))
print(next(my_sentence))
print(next(my_sentence))
print(next(my_sentence))

---------------------------------

is
a
test
print(next(my_sentence))
File "C:\Users\purunet\Documents\py9\ii.py", line 14, in __next__
raise StopIteration
StopIteration

---------------------------------

class Sentence:

def __init__(self, sentence):
self.sentence = sentence
self.index = 0
self.words = self.sentence.split()

def __iter__(self):
return self

def __next__(self):
if self.index >= len(self.words):
raise StopIteration
index = self.index
self.index += 1
return self.words[index]

def sentence(sentence):
for word in sentence.split():
yield word

my_sentence = sentence('This is a test')

for word in my_sentence:
print(word)

---------------------------------

This
is
a
test

==========================================

6/07/2020

Python - Itertools Module : Iterator Functions for Efficient Looping

Python - Coding Problem: Creating Your Own Iterators

LinuxerHAN

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