1. Assignment Game
Let's review what happened yesterday
1. importing a module is equivalent to executing the py file
2. Modules will not be imported repeatedly
3. The imported modules are stored in sysmodules
4. What happens after importing the module:
First see if the module is in sys.modules, if not:
Generate a namespace that belongs to the module
execute py file
Create a variable with the same name as the py file to reference the name in this space
Put the imported module in sys.modules
5.from ...import....
6. Absolute and relative imports
7. Software Development Specifications
draw
from collections import namedtuple
Card = namedtuple('Card', ['rand', 'suit']) # Define 2 attributes, card face and suit
class FranchDeck:
ranks = [str(n) for n in range(2, 11)] + list('JQKA') # list comprehension + list, combined into 13 cards
suits = ['heart', 'square board', 'club', 'spade'] # 4 suits
def __init__(self):
self._cards = [Card(rank, suit) for rank in FranchDeck.ranks
for suit in FranchDeck.suits] # Take out 52 cards and return a list.
# [Card(rand='2', suit='red heart'), Card(rand='2', suit='square board')...]
def __len__(self):
return len(self._cards) # Get the length of the list
def __getitem__(self, item):
return self._cards[item] # Take a card
deck = FranchDeck()
print(deck[0]) # take the first card
from random import choice
print(choice(deck)) # randomly choose a card
print(choice(deck))
The above code relies on __len__ and __getitem__ to draw cards, and the cards you get are different each time.
describe a card
from collections import namedtuple
Card = namedtuple('Card',['rand','suit']) #Define 2 attributes, card face and suit
print(Card('2','Red Heart'))
from collections import namedtuple
Card = namedtuple('Card', ['rand', 'suit']) # Define 2 attributes, card face and suit
class FranchDeck:
ranks = [str(n) for n in range(2, 11)] + list('JQKA')
suits = ['Hearts', 'Square', 'Clubs', 'Spades']
def __init__(self):
self._cards = [Card(rank, suit) for rank in FranchDeck.ranks
for suit in FranchDeck.suits]
def __len__(self):
return len(self._cards)
def __getitem__(self, item):
return self._cards[item]
def __setitem__(self, key, value):
self._cards[key] = value
deck = FranchDeck()
# print(deck[0]) #Draw the first card
from random import choice
# print(choice(deck))
# print(choice(deck))
from random import shuffle
shuffle(deck) # shuffle the order, shuffle
# print(deck[:5]) # Draw 5 cards
print(deck[:]) # , 52 cards are different each time.
Second, exceptions and errors
Errors are inevitable in the program, and errors are divided into two minutes
1. Syntax error (this kind of error cannot pass the syntax detection of the python interpreter and must be corrected before the program is executed)
if name = 10 #2. Logic Error num = 0 100/num
This blue link information is made by Pycharm, it can jump to the specified code location
ZeroDivisionError is reported by the python interpreter
what is an exception
An exception is a signal that an error occurs when the program is running. In python, the wrong exception is as follows
An exception is a signal that an error occurs when the program is running. In python, the exception triggered by the error is as follows
Types of exceptions in python
Different exceptions in python can be identified by different types (classes and types are unified in python, and types are classes), different class objects identify different exceptions, and an exception identifies an error
trigger IndexError
|
1
2
|
l
=
[
'egon'
,
'aa'
]
l[
3
]
|
trigger KeyError
|
1
2
|
dic
=
{
'name'
:
'egon'
}
dic[
'age'
]
|
trigger ValueError
|
1
2
|
s
=
'hello'
int
(s)
|
Common exception
AttributeError attempting to access a tree that an object does not have, such as foo.x, but foo has no attribute x IOError input/output exception; basically the file cannot be opened ImportError cannot import module or package; basically path problem or wrong name IndentationError syntax error (subclass of); code is not properly aligned IndexError The subscript index exceeds the sequence boundary, such as trying to access x[5] when x has only three elements KeyError attempting to access a key that does not exist in the dictionary KeyboardInterrupt Ctrl+C is pressed NameError using a variable that has not been assigned to an object SyntaxError Python code is illegal, the code cannot be compiled (personally think this is a syntax error, written wrong) TypeError The incoming object type does not meet the requirements UnboundLocalError attempts to access a local variable that has not been set, basically because there is another global variable with the same name, cause you to think you are accessing it ValueError passes in a value not expected by the caller, even if the value is of the correct type
more exceptions
ArithmeticError AssertionError AttributeError BaseException BufferError BytesWarning DeprecationWarning EnvironmentError EOFError Exception FloatingPointError FutureWarning GeneratorExit ImportError ImportWarning IndentationError IndexError IOError KeyboardInterrupt KeyError LookupError MemoryError NameError NotImplementedError OSError OverflowError PendingDeprecationWarning ReferenceError RuntimeError RuntimeWarning StandardError StopIteration SyntaxError SyntaxWarning SystemError SystemExit TabError TypeError UnboundLocalError UnicodeDecodeError UnicodeEncodeError UnicodeError UnicodeTranslateError UnicodeWarning UserWarning ValueError Warning ZeroDivisionError