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Head First Python3 in 30 minutes

Packages and Builtin Functions

dir()
float()
int()
len()
list()
max()
min()
print()
round()
str()
type()
abs()
help()

Data Types

<class "int">
<class "float">
<class "str">

x = 3+5j
x.real
x.imag
a = 3
b = 5
c = complex(a, b)

y = bytearray(6)
z = memoryview(bytes(5))

Operators

a = []
b = []
a is b
### False
a == b
### True

Dates

from datetime import date as d
d.today()
str(d.today())

Lists

l.pop()
l.pop(4)
l.append(9)
l.remove(9)
l.count(1)
l.reverse()
l.sort()
len(l)
l[-len(l)]
l[1:3]
l[1:]
l[-1:]
### last one
l[:-1]
### except last one
9 in l
3 not in l
range(1,9,2)

Tuples

### can’t be modified
numbers = (1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
numbers[0]
numbers[-2]
numbers[:-3]
numbers.count(2)
numbers.index(2)

Dictionaries

dict_detail = {}
dict_detail["first name"] = "Rob"

person_details = dict(first_name="Rob", surname="Mastrodomenico",
    gender="Male", favourite_food="Pizza")
personal_details.clear()
personal_details.items()
list(personal_details.items())[0]
personal_details.keys()
personal_details.values()

x = ('key1', 'key2', 'key3')
y = 0
res = dict.fromkeys(x, y)

Sets

### storing unique values
names = {'Tony','Peter','Natasha','Wanda'}
names = set(('Tony','Peter','Natasha','Wanda', 1, 2, 3))
names = set(['Tony','Peter','Natasha','Wanda', 1, 2, 3])
names = set('Wanda')
names.add('Steve')

names.union(more_names)

names & more_names
names.intersection(more_names)
names & more_names & even_more_names

names - more_names
names.difference(more_names)
names - more_names - even_more_names
names.difference(more_names, even_more_names)

names ^ more_names
names.symmetric_difference(more_names)
names | more_names
names.isdisjoint(more_names)
names.issubset(more_names)
names.issuperset(more_names)

names.pop()
names.add('Bruce')
names.remove('Tony')
### if not exists, return KeyError
names.discard('Sue')
### always return True no matter key exists or not
names.clear()

frozen_names = frozenset({'Tony','Peter','Natasha','Wanda'})
### cannot be altered

Strings

single_quote_string = 'string with a \' single quote'
single_quote_string = """string with a ' single quote"""
raw_string = r"This has a \n in it"
not_raw_string = "This has a \\n in it"
name.lower()
name.upper()
name.split(" ")
match_details.replace(",",":")
match_details = ','.join(details)

Regular Expressions

import re
re.findall("[a-m]", name)
### find specific character
re.findall("\d", txt)
re.findall("[0-9]", txt)
### find integer
re.findall("he..o", txt)
re.findall("^start", txt)
re.findall("end$", txt)
re.findall("aix*", txt)
### ai followed by 0 or more x
re.findall("aix+", txt)
### ai followed by one or more x
re.findall("mo{2}", txt)
re.findall("avengers|heroes", txt)
re.findall("\s", txt)
### find space
re.split("\s", txt, maxsplit=2)
re.sub("\s", "9", txt, 3)
re.search("ai", txt)
  • \A: “\AIt”
  • \b: at the beginning or at the end of a word
  • \B: NOT at the beginning (or at the end) of a word
  • \d: digits (numbers from 0-9)
  • \D: DOES NOT contain digits
  • \s: white space character
  • \S: DOES NOT contain a white space character
  • \w: any word characters (characters from a to Z, digits from 0-9, and the underscore _ character)
  • \W: DOES NOT contain any word characters

Reference

  • The Python Book (Rob Mastrodomenico)
  • https://regexr.com

Disclaimer
  1. License under CC BY-NC 4.0
  2. Copyright issue feedback: dig +short txt issue.imzye.com
  3. Not all the commands and scripts are tested in production environment, use at your own risk
  4. No privacy information is collected here
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