Python笔记

1 Quick Start

Install python2.7 from https://www.python.org/downloads/

Install pip:

$ curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py
$ sudo python get-pip.py

2 Basics

2.1 Numbers

Python 2.7.9 (default, Mar  1 2015, 12:57:24) 
>>> a = 3.23
>>> b = 4
>>> c = 52.3E-4
>>> print a, b, c
3.23 4 0.00523

2.2 Strings

#!/usr/bin/python

str_1 = 'Jack Tan'
str_2 = "Ga Xiao Duo"
str_3 = '''This is a multi-line string. first line.
second line'''

# using the startswith method of the string object
if str_1.startswith('Ja'):
    print("Yes, str_1 start with 'Ja'")

if 'a' in str_1:
    print('Yes, str_1 contains the string "a"')

substr = 'ac'
if str_1.find(substr) != -1:
    print('Yes, str_1 contains the string "{0}"'.format(substr))
    print('Yes, {0} contains the string "{1}"'.format('str_1', substr))
    print('Yes, {} contains the string "{}"'.format('str_1', substr))
    # using the format method of the string object

deli = '_*_'
mylist = ['Brazil', 'Russia', 'India', 'China']

# using the join method of the string object
print(deli.join(mylist))

Output:

Yes, name start with 'Ja'
Yes, name contains the string "a"
Yes, name contains the string "ac"
Brazil_*_Russia_*_India_*_China

Once your have created a string, you cannot change it

2.3 Variable

Python refers to anything used in a program as an object.

Do not need type declaration of variable in python

Python 2.7.9 (default, Mar  1 2015, 12:57:24) 
>>> a = 3.1415
>>> b = 100000
>>> c = 'Jack Tan'
>>> d = ['x1', 'x2']
>>> print a, b, c, d
3.1415 100000 Jack Tan ['x1', 'x2']

.

Variables can hold values of different types called data types. The basic types are numbers and strings. We can create our own types using classes.

2.4 Indentation

Leading whitespace (spaces and tabs) at the beginning of the logical line is used to determine the indentation level of the logical line, which in turn is used to determine the grouping of statements.

Statements which go together must have the same indentation. Each usch set of statements is called a block

10 Resource

• Online Python: http://www.compileonline.com/execute_python_online.php

• Python Quick Start: http://www.tutorialspoint.com/python/python_lists.htm