Python Learning D3

Initial knowledge of basic types

2.1 Numeric int.

The number is mainly used for computing, not many ways to use, just remember one can:

2.2 String str stores a small amount of data

' Alex ', ' 1235443543 '

' [A.] '

3.3 Boolean bool

True False

4.4 List Lists various data types of data, a large amount of data, easy to operate.

[' name ', true,[] .....],

5.5 Yuan zu tupe Read-only list

Use () to denote (a)

6.6 Dictionary Dict stores large amounts of data, relational data. Store data in the form of key-value pairs (key-value)

{' name ': ' Old boy ',

' Name_list ': [' negative ',.....]

' Alex ': {' age ': 40,

' Hobby ': ' Old_women ',

}

},

7.7 Set

{' Wusir ', ' Alex ', ...}

The specific usage

Int

#i = 100#print (I.bit_length ()) Decimal to the number of significant digits converted to binary 1 0000 0001 2 0000 0010 3 0000 0011 100 BOOL

int <---> str mutual conversion str---> int int (str)Condition: The string must consist entirely of numbers. # age = Int (input (' >>> ')) # Print (Age,type (age)) int---> str str (int)# S1 = str (123) # s2 = 123 # Print (S1, type (S1)) # Print (S2, type (s2))

BOOL <---> int BOOL---> intTrue--->1 False---> 0# print (int (True)) # Print (int (False)) int---> BOOLNonzero is true and 0 is false. # print (bool) # print (bool ( -1)) # print (bool (0)) Str                        

  i = ' python12 period '

IndexStarting from 0, the calculation is sequentially 0. 1.2.           .... From right to left is-1-2-3 .....

# i1 = i[0] # print (I1) # i2 = i[4] # print (I2) # i3 =i[-1] # print (i3)

slices

(Gu Tou Disregard butt)

# i4 = I[0:6] # print (i4) # i5 = i[:6] # Print (i5)   python#  I6 = i[1:4]#  print (I6)   Yth#  i7 =i[5:]#  print (i7)    N12 period #  i8 = i[:]# print (i8)    Python12 period

Step Size

# I9 = i[:5:2]     front empty is the beginning to 5 steps for 2#  print (I9)       PTO#  i10 = i[4::2]   Intermediate empty is the end 4 to end Step 2#  print (i10)      O1 period #  i11 = i[-1:-5:-1]     from back to forward step 1 # print (I11)            period 21n#  i12 = i[-3:-1]       slice from 3 to 2 (Gu Tou regardless of tail)#  print ( I12)            

common ways to manipulate strings

s = ' Laonanhai '

* * Capitalize first letter uppercase, the remaining letters lowercase.

# S1 = s.capitalize () # print (S1)           # Laonanhai

* Center Center. The first parameter determines the size, * indicates padding left and right parts

# s2 = s.center ("*") # print (s2)          #***laonanhai***

* * * Upper full capitalizationLower Full lowercase

# s3 = S.upper () # s31 er () # Print (S3)           Laonanhai#  print (s31)         Laonanhai

PS

# code = ' Qadr '. Upper () # Your_code = input (' Please enter a verification code, not case sensitive: '). Upper () # if Your_code = = Code: # print (' Verification successful ')

StartsWith: Determine what content starts with, return bool, can slice, slice, separate

EndsWith:

StartsWith (self, prefix, Start=none, End=none)

# S4 = S.startswith (' l ') # s41 = S.startswith (' Lao ') # s42 = S.startswith (' N ', 3, 6) # print (S42)        True#  print (S4)          true#  print (s41)        False

* Swapcase: Case Flip

# S5 = s.swapcase () # Print (S5)

* Title: Capitalize the first letter of each word not separated by letter

# ss = ' gdsj Wusir6taibai*ritian ' # s6 = Ss.title () # Print (S6)

* * * Index: Indexed by the element, can be sliced, unable to find an error. * * * Find: Indexed by element, can be sliced, cannot find return-1

# s7 = S.find (' a ') # s71 = s.find (' A ', 2,)       2 find #  s71 = s.find (' Q ',)#  print (s71)#< from the second start /c9> s72 = S.index (' Q ')#  print (s72)#  print (s71)# ss = ' \talex\n ' # Print (ss)

* * * Strip remove the front and back space, line break \ n, tab (tab \ t)You can also remove the specified characters before and after (must be in order of occurrence)

# ss = ' Ablabsexsba ' # S9 = Ss.strip (' a ') # S9 = Ss.strip (' abs ') # Lstrip ()        remove    # Rstrip () starting from the left to remove # print (S9)       from the right  

PS prevents the user from sliding the input spaces or other whitespace characters

Username = input (' Please enter user name '). Strip ()if' Bowl rong ' : Print (' login successful ')

* * * Split str---> Listseparated by a space by default

# s = ' wusir Alex Taibai ' # st = ' Wusir,alex,taibai ' # st1 = ' Qwusirqalexqtaibai ' # s10 = S.split () # print (S10) # s101 = St.split (', ') # print (s101) # s102 = st1.split (' Q ', 2)     2 represents the first two Q to split #  print (s102)

Join in some cases, List---> str

# s = ' Alex ' # S11 = ' + '. Join (s) # print (S11) # L = [' Wusir ', ' Alex ', ' Taibai '] # s111 = ". Join (L) # Print (S111,type (s111))

* * Repalce replaces specified characters

Replace (self, old, new, Count=none)

# s = ' small matte pink ghlasdfg little Pink ' # # s12 = S.replace (' Little pink ', ' big Hammer ') # S12 = S.replace (' Little pink ', ' big Hammer ', 2)   number 2 means replace only the first two characters #  print (s12)

Public methods

' Fdsajlskgjdsaf;jdskfsdaf '

Len () Total number

# print (len (s))

Count (') calculates the number of occurrences of some elements, which can be sliced

# C1 = S.count (' f ')   # Print (c1)

Format formatted output

Three different ways

# msg = ' My name {}, this year {}, hobby {} '. Format (' Taibai ', ' ' Girl ') # Print (msg)

# msg = ' I call {0}, this year {1}, hobby {2}, I still call {0} '. Format (' Taibai ', ' ' "', ' Girl ') # Print (msg)

# msg = ' My name {name}, this year {age}, hobby {hobby} '. # format (name= ' Taibai ', hobby= ' girl ', age= ') # Print (msg)

Judgment statement

# name= ' jinxin123 ' # print (Name.isalnum ()) #字符串由字母或数字组成    True#  print (Name.isalpha ()) #字符串只由字母组成             False#  print (name.isdigit ()) #字符串只由数字组成              False

Ps

Python Learning D3