A: List:
names=["4ZhangYang","Guyun","xXiangPeng",["alex","jack"],"ChenRonghua","XuLiangchen"]
print (names [1: 3]) # Hand care regardless of the end sections, the second extraction / three
print (names [3]) # fourth sections taken
print (names [-2:]) # last two sections taken
#increase:
names.append ( "LeiHaidong") # Finally join
names.insert (1, "ChenRonghua") # into the front guyun
#delete delete three ways
names.remove("ChenRonghua")
del names[1]=names.pop(1)
names.pop(1)
#modify
names [2] = "Peng to" Modify #
print (names.count ( "ChenRonghua")) # calculate the number of chenronghua appear
names.clear () # Empty
names.reverse () # reverse reverse
names.sort () # sorted alphabetically
print(names)
names2=[1,2,3,4]
names
names.extend (names2) # merge tuple
the names2
print(names,names2)
Three printing methods:
print(names[0:-1:2])
print (names [:: 2]) # 0 can be omitted
print(names[:])
Two: tuple:
And the list is basically the same, almost:
1 . Not CRUD
2 . Small brackets in place of brackets
3 . But you can use statistics and view: count and index
Added: Remove the list subscript
Three: String
Can not be modified.
name = "my \tname is {name} and i am {year} old"
Common applications of string functions:
print (name.capitalize ()) # capitalized
The number of print (name.count ( "a")) # statistics appear
print (name.center (50, "-")) # 50 spaces, insufficient - padded
print (name.endswith ( "ex")) # what end
print (name.expandtabs (tabsize = 30)) # \ t turn into 30 spaces
print (name [name.find ( "name"):]) #find ( "name") returns 4, the string may be sliced
print (name.format (name = 'alex', year = 23)) # Format
print(name.format_map( {'name':'alex','year':12} )) #字典
print ( 'ab23'.isalnum ()) # determines whether or Arabic numerals
print ( 'abA'.isalpha ()) # if it is pure English characters
print ( '1A'.isdecimal ()) # is a decimal
print ( '1A'.isdigit ()) # whether the integer
print ( 'a 1A'.isidentifier ()) # interpretation is not a valid identifier
print ( '33A'.isnumeric ()) # whether a number
print ( 'My Name Is' .istitle ()) # whether the title, capitalize the first letter of each
print ( 'My Name Is' .isprintable ()) #tty file, drive file is unprintable
print ( 'My Name Is' .isupper ()) # is not capitalized
print (. '+' join ([ '1', '2', '3'])) # 2 + 3 + 1 represents; often
print (name.ljust (50, '*')) # 50 long, make up the shortage with *, up in the final (Last)
print (name.rjust (50, '-')) # 50 length, with less than - fill
print ( 'Alex'.lower ()) # all lowercase
print( 'Alex'.upper() )
print ( '\ nAlex'.lstrip ()) # to the left of the spaces and line breaks
print( 'Alex\n'.rstrip() )
print( ' Alex\n'.strip() )
p = str.maketrans ( "abcdefli", '123 $ @ 456') # Alternatively, for example into a 1, may be used as the password
print("alex li".translate(p) )
print ( 'alex li'.replace (' l ',' L ', 1)) # l is the replacement of an L
print ( 'alex lil'.rfind (' l ')) # 5 return, from the left to find the maximum number of index
print ( '1 + 2 + 3 + 4'.split (' + ')) # segmentation according to what
print('1+2\n+3+4'.splitlines())
print ( 'Alex Li'.swapcase ()) # sensitive conversion
print ( 'lex li'.title ()) # capitalized
print ( 'lex li'.zfill (50)) # fill bits
Four: Dictionary
Note: Key Try not to write Chinese:
info = {
'stu1101': "TengLan Wu",
'Stu1102': "LongZe Luola",
'stu1103': "XiaoZe Maliya",
}
check:
info [ 'stu1104'] # being given absent
print (info.get ( 'stu1103')) # does not exist will return null
modify:
info["stu1101"] ="武藤兰"
increase:
info["stu1104"] ="CangJing"
delete:
#of the
#del info["stu1101"]
info.pop("stu1101")
info.popitem () # delete a random
Update:
b ={
'stu1101': "Alex",
1:3,
2:5
}
info.update (b) # merge two dictionaries, and set to take
print (info.items ()) # convert into a dictionary list
Two kinds of dictionaries cycle:
for i in info:
print(i,info[i])
for k,v in info.items():
print (k, v)
Difference: the first is more efficient, to become the second first list of conversion.
Multi-level nested dictionaries and operations
av_catalog = {
"Europe": {
" Www.youporn.com ": [ "a lot of free, the world's largest", "quality in general"],
" Www.pornhub.com ": [ "a lot of free, are also high," "high quality than yourporn"],
"Letmedothistoyou.com": [ "mostly selfie, a lot of high-quality images," "limited resources, updating slow"],
"X-art.com": [ "the quality is very high, really high," "all the charges, please bypass ratio Cock"]
},
"Japan and South Korea": {
"Tokyo-hot": [ "What quality do not know, personally do not like Japan and South Korea have been the norm," "I heard a fee."]
},
"mainland":{
"1024": [ "all free, good, good life of peace", "server in a foreign country, slow"]
}
}
#modify:
av_catalog [ "continent"] [ "1024"] [1] = "can make a mirror at home."
av_catalog.setdefault ( "Continental", { "www.baidu.com": [1,2]}) # can take to, return, take less, to reset
Three-level menu examples:
Five: collection
Is a set of unordered not repeated combinations of data, his role is as follows:
Deduplication:
list_1 = [1,4,5,7,3,6,7,9]
list_1 = set(list_1)
list_2 =set([2,6,0,66,22,8,4])
print(list_1,list_2)
# Intersection
print( list_1.intersection(list_2) )
# Union
print(list_1.union(list_2))
#差集 in list_1 but not in list_2
print (list_1.difference (list_2)) # Save common binding portion 1
# Child Collection
list_3 = set([1,3,7])
print subset (list_3.issubset (list_1)) # 3 is 1 of
print superset (list_1.issuperset (list_3)) # 1 whether or 3
# Symmetric difference
print (list_1.symmetric_difference (list_2)) # union minus the intersection
list_4 = set([5,6,7,8])
print (list_3.isdisjoint (list_4)) # Return True if two sets have a null intersection. there was no communication (false)
# Intersection
print(list_1 & list_2)
# Union
print(list_2 | list_1)
# Difference set
print(list_1 - list_2) # in list 1 but not in list 2
# Symmetric difference
print(list_1 ^ list_2)
list_1.add (999) # increased
list_1.update ([888,777,555]) # Review
list_1.remove (999) # delete one, there will be an error
print (list_1.discard (888)) # specify a value, if there is deleted, if there is no operation
print (list_1.pop ()) # delete any of
六：文件
#data = open("yesterday",encoding="utf-8").read()
f = open ( "yesterday2", 'a', encoding = "utf-8") # filehandle
#a = append additional
f.write("\nwhen i was young i listen to the radio\n")
data = f.read()
print('--read',data)
f.close()
print (f.encoding) # print type, as herein utf-8
print(dir(f.buffer) ) #
Open = F ( "yesterday2", 'R & lt', encoding = "UTF-. 8") # filehandle
#high bige
count = 0
for line in f:
if count == 9:
print ( '---- I am dividing line ----------')
count += 1
continue
print(line)
count +=1
#low loop
for index,line in enumerate(f.readlines()):
if index == 9:
print ( '---- I am dividing line ----------')
continue
print(line.strip())
#for i in range(5):
# print(f.readline())
'''
Open = F ( "yesterday2", 'R & lt', encoding = "UTF-. 8") # filehandle
print (f.tell ()) # letter Location
print (f.readline (20)) # How many characters take
print(f.tell())
f.seek (9) # from a few start
print('2------',f.readline())
print (f.writable ()) # is writable
f.flush () # to force a refresh to the hard disk, not a full refresh
Example 1: promptly flushed out
Example 2: Production of the progress bar;
Import sys,time
For I in range(20):
sys.stdout.write("#")
sys.stdout.flush()
time.sleep(0.1)
Open = F ( "yesterday2", 'A', encoding = "UTF-. 8") # filehandle
f.seek (10) # from a few start
f.truncate (20) # 20 cutoff to retain, remove the back
f = open ( "yesterday2", 'r +', encoding = "utf-8") # write, open, continue to write the content. Most used
f = open ( "yesterday2", 'w +', encoding = "utf-8") # read-write file handle, no far-reaching
f = open ( "yesterday2", 'a +', encoding = "utf-8") # additional write file handle
f = open ( "yesterday2", 'rb') # binary read for network transmission
f = open("yesterday2",'wb') #二进制写，不能读
f.write("hello binary\n".encode())
f.close()
备注：Open ： r w a r+ w+ a+ rb wb ab
#实例：将yesterday2拷贝到新建的yesterday2bak中，并修改部分
import sys
f = open("yesterday2","r",encoding="utf-8")
f_new = open("yesterday2bak","w",encoding="utf-8")
for line in f:
if "我的双眼却视而不见" in line:
line=line.replace("我的双眼却视而不见","wangbao的双眼却视而不见")
f_new.write(line)
f.close()
f_new.close()
实例：打开多个文件，且不用关心文件关闭问题，这种自动关闭
import sys
#可以打开多个文件
with open("yesterday2","r",encoding="utf-8") as f ,\
open("yesterday2", "r", encoding="utf-8") as f2:
for line in f:
print(line)
七：字符串编码转换
7.1 在python2中：默认utf-8
Utf-8转成Unicode，再转成GBK
GBK转UTF-8也要先转成Unicode
7.2 在python3中：默认unicode（都是两个字节）
#-*-coding:gbk-*- #文件中申明为gbk
import sys
print(sys.getdefaultencoding())
__author__ = "Alex Li"
s = "你哈" #本python中还是使用Unicode
print(s.encode("gbk"))
print(s.encode("utf-8"))
print(s.encode("utf-8").decode("utf-8").encode("gb2312").decode("gb2312"))