1, the string
1.1, how to use Python string
a, single quotation marks ( ')
in single quotes string represents, for example:
str='this is string';
print str;B, using the double quotes ( ")
String Usage double quotes string identical single quotes, for example:
str="this is string";
print str;C, using a three-quotation marks ( '' ')
using the three quoted string representing a multi-line, single quotes may be used freely in the three quotes and double quotes, for example:
'''
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'''
str='''this is string
this is pythod string
this is string'''
print str;2, Boolean type
bool=False;
print bool;
bool=True;
print bool;3, integer
int=20;
print int;4, floating point
float=2.3;
print float;5, numbers
including integer, floating point.
5.1, delete digital object reference, for example:
a=1;
b=2;
c=3;
del a;
del b, c;
\#print a; #删除a变量后，再调用a变量会报错5.2, numeric conversion
'''
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'''
int(x [,base]) 将x转换为一个整数
float(x ) 将x转换到一个浮点数
complex(real [,imag]) 创建一个复数
str(x) 将对象x转换为字符串
repr(x) 将对象x转换为表达式字符串
eval(str) 用来计算在字符串中的有效Python表达式,并返回一个对象
tuple(s) 将序列s转换为一个元组
list(s) 将序列s转换为一个列表
chr(x) 将一个整数转换为一个字符
unichr(x) 将一个整数转换为Unicode字符
ord(x) 将一个字符转换为它的整数值
hex(x) 将一个整数转换为一个十六进制字符串
oct(x) 将一个整数转换为一个八进制字符串5.3 Mathematical Functions
'''
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'''
abs(x) 返回数字的绝对值，如abs(-10) 返回 10
ceil(x) 返回数字的上入整数，如math.ceil(4.1) 返回 5
cmp(x, y) 如果 x < y 返回 -1, 如果 x == y 返回 0, 如果 x > y 返回 1
exp(x) 返回e的x次幂(ex),如math.exp(1) 返回2.718281828459045
fabs(x) 返回数字的绝对值，如math.fabs(-10) 返回10.0
floor(x) 返回数字的下舍整数，如math.floor(4.9)返回 4
log(x) 如math.log(math.e)返回1.0,math.log(100,10)返回2.0
log10(x) 返回以10为基数的x的对数，如math.log10(100)返回 2.0
max(x1, x2,...) 返回给定参数的最大值，参数可以为序列。
min(x1, x2,...) 返回给定参数的最小值，参数可以为序列。
modf(x) 返回x的整数部分与小数部分，两部分的数值符号与x相同，整数部分以浮点型表示。
pow(x, y) x**y 运算后的值。
round(x [,n]) 返回浮点数x的四舍五入值，如给出n值，则代表舍入到小数点后的位数。
sqrt(x) 返回数字x的平方根，数字可以为负数，返回类型为实数，如math.sqrt(4)返回 2+0j6, a listing
6.1, the initialization list, for example:
list=['physics', 'chemistry', 1997, 2000];
nums=[1, 3, 5, 7, 8, 13, 20];6.2, access the list of values, such as:
'''
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'''
'''nums[0]: 1'''
print "nums[0]:", nums[0]
'''nums[2:5]: [5, 7, 8] 从下标为2的元素切割到下标为5的元素，但不包含下标为5的元素'''
print "nums[2:5]:", nums[2:5]
'''nums[1:]: [3, 5, 7, 8, 13, 20] 从下标为1切割到最后一个元素'''
print "nums[1:]:", nums[1:]
'''nums[:-3]: [1, 3, 5, 7] 从最开始的元素一直切割到倒数第3个元素，但不包含倒数第三个元素'''
print "nums[:-3]:", nums[:-3]
'''nums[:]: [1, 3, 5, 7, 8, 13, 20] 返回所有元素'''
print "nums[:]:", nums[:]6.3, update the list, such as:
nums[0]="ljq";
print nums[0];6.4, delete list elements
del nums[0];
'''nums[:]: [3, 5, 7, 8, 13, 20]'''
print "nums[:]:", nums[:];6.5, operator list script
list of + and similar string operators. + Sign for the combined list, numbers for repeating the list, for example:
'''
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'''
print len([1, 2, 3]); #3
print [1, 2, 3] + [4, 5, 6]; #[1, 2, 3, 4, 5, 6]
print ['Hi!'] * 4; #['Hi!', 'Hi!', 'Hi!', 'Hi!']
print 3 in [1, 2, 3] #True
for x in [1, 2, 3]: print x, #1 2 36.6 interception list
L=['spam', 'Spam', 'SPAM!'];
print L[2]; #'SPAM!'
print L[-2]; #'Spam'
print L[1:]; #['Spam', 'SPAM!']6.7, the list of functions & methods
'''
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'''
list.append(obj) 在列表末尾添加新的对象
list.count(obj) 统计某个元素在列表中出现的次数
list.extend(seq) 在列表末尾一次性追加另一个序列中的多个值(用新列表扩展原来的列表)
list.index(obj) 从列表中找出某个值第一个匹配项的索引位置，索引从0开始
list.insert(index, obj) 将对象插入列表
list.pop(obj=list[-1]) 移除列表中的一个元素(默认最后一个元素)，并且返回该元素的值
list.remove(obj) 移除列表中某个值的第一个匹配项
list.reverse() 反向列表中元素，倒转
list.sort([func]) 对原列表进行排序7, the tuple (tuple)
Similar tuple Python list, except that the elements of the tuple can not be modified; tuple using parentheses (), a list of square brackets []; tuple created is very simple, only you need to add elements in parentheses, using comma (,) can be separated, for example:
tup1 = ('physics', 'chemistry', 1997, 2000);
tup2 = (1, 2, 3, 4, 5 );
tup3 = "a", "b", "c", "d";Empty tuples, for example: tup = ();
Tuple only one element, the element needs to be added after the comma, for example: tup1 = (50,);
Tuple string Similarly, the subscript index starts from 0, may be taken, and other combinations.
7.1, visit tuple
tup1 = ('physics', 'chemistry', 1997, 2000);
#tup1[0]: physics
print "tup1[0]: ", tup1[0]
#tup1[1:5]: ('chemistry', 1997)
print "tup1[1:5]: ", tup1[1:3]7.2, modify tuple
element values tuple can not be modified, but we may be connected to a combination of tuples, for example:
tup1 = (12, 34.56);
tup2 = ('abc', 'xyz');# The following modifications tuple element operation is illegal.
# Tup1 [0] = 100;
# Create a new tuple
tup3 = tup1 + tup2;
print tup3; #(12, 34.56, 'abc', 'xyz')7.3, delete tuple
element values in the tuple is not allowed to delete, you can use the del statement to delete an entire tuple, for example:
tup = ('physics', 'chemistry', 1997, 2000);
print tup;
del tup;7.4, operator tuple
string as + and * can be used for operation between the number of tuples. This means that they can be combined and after replication operation will generate a new tuple.
7.5, & taken index tuple
L = ('spam', 'Spam', 'SPAM!');
print L[2]; #'SPAM!'
print L[-2]; #'Spam'
print L[1:]; #['Spam', 'SPAM!']7.6, built-in functions tuple
'''
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'''
cmp(tuple1, tuple2) 比较两个元组元素。
len(tuple) 计算元组元素个数。
max(tuple) 返回元组中元素最大值。
min(tuple) 返回元组中元素最小值。
tuple(seq) 将列表转换为元组。8, Dictionary
8.1 Introduction dictionary
Dictionary (dictionary) python is outside the list of the most flexible structure of built-in data types other. Is an ordered list of target binding, dictionaries are unordered collections of objects. The difference between the two is that: among the elements of the dictionary is accessed by a key, rather than by shifting access.
The dictionary by the key and the corresponding values. Dictionary also referred associative array or hash table. The basic syntax is as follows:
dict = {'Alice': '2341', 'Beth': '9102', 'Cecil': '3258'};So also create a dictionary:
dict1 = { 'abc': 456 };
dict2 = { 'abc': 123, 98.6: 37 };Each key value must be separated by a colon (:), each pair separated by commas, the whole in curly braces ({}). Key must be unique, but the value is not necessary; type of data may take any value, but must be immutable, such as a string, or the number of tuples.
8.2, access to the dictionary values
#!/usr/bin/python
dict = {'name': 'Zara', 'age': 7, 'class': 'First'};
print "dict['name']: ", dict['name'];
print "dict['age']: ", dict['age'];8.3, modify the dictionary
to add new content to the dictionary method is to add a new key / value pairs, modify or delete existing key / value pairs in the following examples:
'''
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'''
#!/usr/bin/python
dict = {'name': 'Zara', 'age': 7, 'class': 'First'};
dict["age"]=27; #修改已有键的值
dict["school"]="wutong"; #增加新的键/值对
print "dict['age']: ", dict['age'];
print "dict['school']: ", dict['school'];8.4, deleting dictionary
del dict [ 'name']; # delete key is 'name' entry
dict.clear (); # Clear all dictionary entries
del dict; # remove dictionaries
example:
#!/usr/bin/python
dict = {'name': 'Zara', 'age': 7, 'class': 'First'};
del dict['name'];
#dict {'age': 7, 'class': 'First'}
print "dict", dict;Note: The dictionary does not exist, del raises an exception
8.5, built-in functions & dictionary method
'''
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'''
cmp(dict1, dict2) 比较两个字典元素。
len(dict) 计算字典元素个数，即键的总数。
str(dict) 输出字典可打印的字符串表示。
type(variable) 返回输入的变量类型，如果变量是字典就返回字典类型。
radiansdict.clear() 删除字典内所有元素
radiansdict.copy() 返回一个字典的浅复制
radiansdict.fromkeys() 创建一个新字典，以序列seq中元素做字典的键，val为字典所有键对应的初始值
radiansdict.get(key, default=None) 返回指定键的值，如果值不在字典中返回default值
radiansdict.has_key(key) 如果键在字典dict里返回true，否则返回false
radiansdict.items() 以列表返回可遍历的(键, 值) 元组数组
radiansdict.keys() 以列表返回一个字典所有的键
radiansdict.setdefault(key, default=None) 和get()类似, 但如果键不已经存在于字典中，将会添加键并将值设为default
radiansdict.update(dict2) 把字典dict2的键/值对更新到dict里
radiansdict.values() 以列表返回字典中的所有值9, the date and time
9.1, obtain the current time, for example:
import time, datetime;
localtime = time.localtime(time.time())
\#Local current time : time.struct_time(tm_year=2014, tm_mon=3, tm_mday=21, tm_hour=15, tm_min=13, tm_sec=56, tm_wday=4, tm_yday=80, tm_isdst=0)
print "Local current time :", localtimeDescription: time.struct_time (tm_year = 2014, tm_mon = 3, tm_mday = 21, tm_hour = 15, tm_min = 13, tm_sec = 56, tm_wday = 4, tm_yday = 80, tm_isdst = 0) belonging struct_time tuple, struct_time tuple It has the following attributes:
9.2, obtaining formatting time
can be selected according to the needs of a variety of formats, but the easiest time to get the function-readable pattern is the asctime ():
2.1, into a string date
首选：print time.strftime('%Y-%m-%d %H:%M:%S');
其次：print datetime.datetime.strftime(datetime.datetime.now(), '%Y-%m-%d %H:%M:%S')
最后：print str(datetime.datetime.now())[:19]2.2, string into the date
expire_time = "2013-05-21 09:50:35"
d = datetime.datetime.strptime(expire_time,"%Y-%m-%d %H:%M:%S")
print d;9.3, the difference between the date of acquisition
'''
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'''
oneday = datetime.timedelta(days=1)
#今天，2014-03-21
today = datetime.date.today()
#昨天，2014-03-20
yesterday = datetime.date.today() - oneday
#明天，2014-03-22
tomorrow = datetime.date.today() + oneday
#获取今天零点的时间，2014-03-21 00:00:00
today_zero_time = datetime.datetime.strftime(today, '%Y-%m-%d %H:%M:%S')
#0:00:00.001000
print datetime.timedelta(milliseconds=1), #1毫秒
#0:00:01
print datetime.timedelta(seconds=1), #1秒
#0:01:00
print datetime.timedelta(minutes=1), #1分钟
#1:00:00
print datetime.timedelta(hours=1), #1小时
#1 day, 0:00:00
print datetime.timedelta(days=1), #1天
#7 days, 0:00:00
print datetime.timedelta(weeks=1)9.4, to obtain the time difference
'''
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'''
#1 day, 0:00:00
oneday = datetime.timedelta(days=1)
#今天，2014-03-21 16:07:23.943000
today_time = datetime.datetime.now()
#昨天，2014-03-20 16:07:23.943000
yesterday_time = datetime.datetime.now() - oneday
#明天，2014-03-22 16:07:23.943000
tomorrow_time = datetime.datetime.now() + oneday
注意时间是浮点数，带毫秒。
那么要获取当前时间，需要格式化一下：
print datetime.datetime.strftime(today_time, '%Y-%m-%d %H:%M:%S')
print datetime.datetime.strftime(yesterday_time, '%Y-%m-%d %H:%M:%S')
print datetime.datetime.strftime(tomorrow_time, '%Y-%m-%d %H:%M:%S')9.5, access to the last day of last month
last_month_last_day = datetime.date(datetime.date.today().year,datetime.date.today().month,1)-datetime.timedelta(1)9.6 seconds formatted date string, floating-point return type:
expire_time = "2013-05-21 09:50:35"
d = datetime.datetime.strptime(expire_time,"%Y-%m-%d %H:%M:%S")
time_sec_float = time.mktime(d.timetuple())
print time_sec_float9.7, the date format for the number of seconds, return the floating-point type:
d = datetime.date.today()
time_sec_float = time.mktime(d.timetuple())
print time_sec_float9.8, the number of seconds to String
time_sec = time.time()
print time.strftime("%Y-%m-%d %H:%M:%S", time.localtime(time_sec))