前言
学习Python良久，想全面的回顾一下Python的基础知识，于是阅读了Python3.4的官方教程；在这里做要点的摘录，只为提纲挈领，对细节不做过多的解释。
Control Flow Tools
TODO
Data Structures
list, dict, set, tuple, str
More on Lists
- methods: append(x), extend(L), insert(i, x), remove(x), pop([i]), clear(), index(x), count(x), sort(), reverse(), copy()
- Using Lists as Stacks(OK)
- Using Lists as Queues(Not efficient) -> Using collections.deque
Comprehensions
List/Set/Dictionary Comprehensions
Looping Techniques
- Using the
items()method to loop over dictionaries - Using the
enumerate()function to loop over a sequence - Using the
zip()function to loop over two or more sequences at the same time - Using the
reversed()function to loop over a sequence in reverse - Using the
sorted()function to loop over a sequence in sorted order
Comparing Sequences and Other Types
(1, 2, 3) < (1, 2, 4)
[1, 2, 3] < [1, 2, 4]
'ABC' < 'C' < 'Pascal' < 'Python' # Comparisons can be chained
(1, 2, 3, 4) < (1, 2, 4)
(1, 2) < (1, 2, -1)
(1, 2, 3) == (1.0, 2.0, 3.0)
(1, 2, ('aa', 'ab')) < (1, 2, ('abc', 'a'), 4)
Modules and Packages
Input and Output
Fancier Output Formatting
- The str() function is meant to return representations of values which are fairly human-readable, while repr() is meant to generate representations which can be read by the interpreter
>>> for x in range(1, 11):
... print(repr(x).rjust(2), repr(x*x).rjust(3), end=' ')
... # Note use of 'end' on previous line
... print(repr(x*x*x).rjust(4))
...
1 1 1
2 4 8
3 9 27
4 16 64
5 25 125
6 36 216
7 49 343
8 64 512
9 81 729
10 100 1000
>>> for x in range(1, 11):
... print('{0:2d} {1:3d} {2:4d}'.format(x, x*x, x*x*x))
...
1 1 1
2 4 8
3 9 27
4 16 64
5 25 125
6 36 216
7 49 343
8 64 512
9 81 729
10 100 1000
- str.format()
>>> print('We are the {} who say "{}!"'.format('knights', 'Ni'))
We are the knights who say "Ni!"
>>> print('This {food} is {adjective}.'.format(
... food='spam', adjective='absolutely horrible'))
This spam is absolutely horrible.
>>> print('The story of {0}, {1}, and {other}.'.format('Bill', 'Manfred',other='Georg'))
The story of Bill, Manfred, and Georg.
>>> table = {'Sjoerd': 4127, 'Jack': 4098, 'Dcab': 7678}
>>> for name, phone in table.items():
... print('{0:10} ==> {1:10d}'.format(name, phone))
...
Jack ==> 4098
Dcab ==> 7678
Sjoerd ==> 4127
>>> table = {'Sjoerd': 4127, 'Jack': 4098, 'Dcab': 8637678}
>>> print('Jack: {0[Jack]:d}; Sjoerd: {0[Sjoerd]:d}; '
... 'Dcab: {0[Dcab]:d}'.format(table))
Jack: 4098; Sjoerd: 4127; Dcab: 8637678
>>> table = {'Sjoerd': 4127, 'Jack': 4098, 'Dcab': 8637678}
>>> print('Jack: {Jack:d}; Sjoerd: {Sjoerd:d}; Dcab: {Dcab:d}'.format(**table))
Jack: 4098; Sjoerd: 4127; Dcab: 8637678
Class
A word About Names and Objects
Aliasing has a possibly surprising effect on the semantics of Python code involving mutable objects such as lists, dictionaries, and most other types.
Python Scopes and Namespaces
Odds & Ends
class Employee:
pass
john = Employee() # Create an empty employee record
# Fill the fields of the record
john.name = 'John Doe'
john.dept = 'computer lab'
john.salary = 1000
Iterator & Generator
Iterator
>>> s = 'abc'
>>> it = iter(s)
>>> it
<iterator object at 0x00A1DB50>
>>> next(it)
'a'
>>> next(it)
'b'
>>> next(it)
'c'
>>> next(it)
Traceback (most recent call last):
File "<stdin>", line 1, in ?
next(it)
StopIteration
Generator
>>> def reverse(data):
... for index in range(len(data)-1, -1, -1):
... yield data[index]
>>> for char in reverse('golf'):
... print(char)
...
f
l
o
g
Generator Expressions
>>> sum(i*i for i in range(10)) # sum of squares
285
>>> xvec = [10, 20, 30]
>>> yvec = [7, 5, 3]
>>> sum(x*y for x,y in zip(xvec, yvec)) # dot product
260
>>> from math import pi, sin
>>> sine_table = {x: sin(x*pi/180) for x in range(0, 91)}
>>> unique_words = set(word for line in page for word in line.split())
>>> valedictorian = max((student.gpa, student.name) for student in graduates)
>>> data = 'golf'
>>> list(data[i] for i in range(len(data)-1, -1, -1))
['f', 'l', 'o', 'g']
Brief Tour of Standard Library
TODO