函数式编程
Python语言教程手册
Python是什么?
- 解释性语言
- 多范式
介绍
命令后>>>python
Python 2.7.3 (default, Aug 1 2012, 05:14:39)
[GCC 4.6.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>>
>>> print "Let's learn Python"
Let's learn Python
Numbers
>>> 23 + 43
66
>>> 23 - 45
-22
>>> 23 * 45
1035
>>> 23 ** 4
279841
>>> 23 / 4
5
>>> 23 / 4.0
5.75
>>> 7 % 2
1
表达式
>>> 3 < 2
False
>>> 3 > 2
True
>>> 3 > 2 < 1
False
>>> (3 > 2) and (2 < 1)
False
>>> 3 > 2 > 1 > 0
True
>>> (3 > 2) and (2 > 1) and (1 > 0)
True
>>> 1 or 2
1
>>> 2 or 1
2
>>> 1 + 2 + 3 * 4 + 5
20
1 + 2 + 3 * 4 + 5
↓
3 + 3 * 4 + 5
↓
3 + 12 + 5
↓
15 + 5
↓
20
>>> "python" > "perl"
True
>>> "python" > "java"
True
变量
>>> a = 23
>>> print a
23
>>> a = "Python"
>>> print a
Python
自己动手看看输出什么？
True = False
False = True
print True, False
print 2 > 3
并行分配
>>> language, version = "Python", 2.7
>>> print language, version
Python 2.7
>>> x = 23
>>> x = 23
>>> y = 20
>>> x, y = x, x + y
>>> print x, y
23 43
变量交换
>>> x = 12
>>> y = 21
>>> x, y = y, x
>>> print x, y
21 12
>>>
String字符串
>>> language = "Python"
>>> print language
Python
>>> language = 'Python'
>>> print language
Python
>>> language = """Python"""
>>> print language
Python
>>> description = """Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability.
... It is an expressive language which provides language constructs intended to enable clear programs on both a small and large scale.
... Python supports multiple programming paradigms, including object-oriented, imperative and functional programming styles.
... """
>>> print description
Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability.
It is an expressive language which provides language constructs intended to enable clear programs on both a small and large scale.
Python supports multiple programming paradigms, including object-oriented, imperative and functional programming styles.
>>>
条件
写一个程序发现两个数字中最大的
>>> a = 12
>>> b = 23
>>> if a > b:
... print "a is greater than b"
... else:
... print "b is greater than a"
...
b is greater than a
>>> if a > 0:
... print "a is positive"
... elif a == 0:
... print "a is zero"
... elif a < 0:
... print "a is negative"
...
a is positive
数据结构
List
List是异质数据类型integer, float, string的集合
>>> a = [1, 2, 3]
>>> b = ["Python", 2.73, 3]
>>> len(a)
3
>>> len(b)
3
>>> a[0]
1
>>> a[-1]
3
>>> b[2]
3
>>> [1, 2] + [3, 4]
[1, 2, 3, 4]
>>> all = [a, b]
>>> all[0]
[1, 2, 3]
>>> all[-1]
['Python', 2.73, 3]
>>> all[3]
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
IndexError: list index out of range
>>> all.append("Bangalore")
>>> all
[[1, 2, 3], ['Python', 2.73, 3], 'Bangalore']
>>> del all[-1]
>>> all
[[1, 2, 3], ['Python', 2.73, 3]]
>>> all[1] = "insert"
>>> all
[[1, 2, 3], 'insert']
>>> all
[[1, 2, 3], 'insert']
>>> 'insert' in all
True
>>> range(10)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> range(10, 2)
[]
>>> range(10, 0, -1)
[10, 9, 8, 7, 6, 5, 4, 3, 2, 1]
>>> range(0, 12, 1)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]
range() -> `range([start,] stop[, step]) -> list of integers`
Slicing切片
>>> l = [1, 2, 3, 4, 5, 6, 7]
[1, 2, 3, 4, 5, 6, 7]
>>> l[:2] #first two elements
[1, 2]
>>> l[2:] #exclude first two elements
[3, 4, 5, 6, 7]
>>> l[::2] #every second element
[1, 3, 5, 7]
>>> l[::1] #every element
[1, 2, 3, 4, 5, 6, 7]
>>> l[::3] #every third element
[1, 4, 7]
>>> l[::10] #every tenth element
[1]
>>> l[::-1]
[7, 6, 5, 4, 3, 2, 1]
访问LIST元素
>>> for item in all:
... print item
...
[1, 2, 3]
insert
>>> for number in range(10):
... print number
...
0
1
2
3
4
5
6
7
8
9
发现0 to 9的偶数
>>> for number in range(0, 10):
... if number % 2:
... print number
...
1
3
5
7
9
内置函数 functions
>>> help([])
>>> min([1, 2, 3])
1
>>> max([1, 2, 3])
3
>>> sum([1, 2, 3])
6
>>> pow(2, 3)
8
编写程序，它接受一个数字作为输入，如果能被3，5整除，打印Fizz, Buzz, FizzBuzz 。
import sys
if __name__ == "__main__":
if len(sys.argv) == 2:
number = int(sys.argv[1])
if number % 15 == 0:
print "FizzBuzz"
elif number % 3 == 0:
print "Fizz"
elif number % 5 == 0:
print "Buzz"
else:
print number
else:
print "python filename.py 23 is the format"
下页
一些案例来自 python practice book.
源码下载Github repo: https://github.com/kracekumar/python-training