Python Basics _ Learning Notes

Python Basics _ Learning Notes

Python contains the built-in sequence in 6:

The two common types are: list and Ganso

String, Unicode string, buffer object, Xrange object

The difference between a list and a ganso:

The list can be modified, and the meta-ancestor cannot modify the

Input: You need to define the format of your inputs

Raw_input: Converts any input into a string

Function:

Pow: can be calculated as a power #pow (2,3)

ABS: Absolute value of the number of #abs (-10)

Round: The value can be rounded to a given precision #round (3.456,1)

Module: is an extension that enhances Python functionality

Math: A function of mathematical operations

Floor: To achieve a method #math. Floor (3.9)

Ceil: To achieve a #math of the law. Ceil (3.4)

SQRT: Realize open square #math. sqrt (9)

Cmath: Calculating Imaginary numbers

SQRT: realizes the open square #cmath of imaginary numbers. sqrt (-9)

Methods for translating numbers into strings:

REPR: Can translate numbers into string format #repr (23) or ' 23 '

STR: Values can be translated into string format

Raw string: Each character entered in the original string will be consistent with the way it is written

Print R "Let\ 's Go" will be output as: Let\ ' s Go

Sequence:

List:

Index: All elements in a sequence are numbered and increment from 0.

Sharding: Access to a range of elements by two indexes separated by colons

Max: Determine the maximum number of values in a sequence #max ([1,2,3,4)]

Min: Determine the smallest number of values in a sequence #min ([1,2,3,4])

Len: Determine the length of the sequence #len ([1,2,3,4])

Del: Remove elements from the list #del a[-1]

Append: Append list #a =append (b)

Count: The number of statistical elements #a. COUNT (1)

Extend: Extended list #a. Extend (b)

Index: Finds the indexed #a of the first occurrence of a value. Index (2)

Insert: Inserts the specified value into the specified position #a. Insert (2, ' ma ')

Pop: can be a list of elements, the default is the last one, you can specify #a. Pop () |a.pop (1)

Remove: Removes the first element #a the specified match to. Remove (' ma ')

Reverse: Stores the elements in the list in reverse #a. Reverse ()

Sort: #a the order in which the list is sorted. Sort ()

CMP: Compare two values, return 0, 1, -1 #cmp (up to four)

Ganso

Tuple: Similar to the list function in the sequence #tuple (' ma ') |tuple ([+])

String:

a=1.23

b= ' Long '

Print "num is%d"%a

Print "num is%.2f"%a

Print "Name is%s"%b

Print "Name is%s num was%d float is%.2f"% (b,a,a)

%10D: Indicates the output field length is 10

%010: Indicates the output field length is 10, if not enough can be used 0-padded

%.2F: Indicates that the exact number of digits is 2 decimal places

%-10D: Indicates left alignment, not enough to use space to supplement

String method:

Find: You can find the specified string in a longer character, return the leftmost index position of the string, if no

Returns 0

' This is a example '. Find (' example ') results: 10

' This is a example '. Find (' test ') Result: 1

' This is a example '. Find (' example ', 0,10) results: 1

Join: Used to add elements to a string queue

A= ' Test '

': '. Join (a) is added between each character in the string:

Lower: Returns the lowercase of a string

A= ' This is A EXAMPLE '

A.lower ()

Upper: Returns the uppercase of a string

A= ' This is a example '

A.upper ()

Title: Converting a string to a caption string

A= ' This is a example '

A.title ()

Replace: Replacing the matched string

A= ' This is example '

A.replace (' is ', ' isn't ')

Split: Splits a string based on a given delimiter

A= '/etc/init.d/rc.local '

A.split ('/')

Strip: Removing spaces on both sides of a string

A= ' This is a example '

A.strip ()

Dictionary:

Find his definition (value) by looking for a specific word (key)

The keys in the dictionary are unique, and the values are not unique

dict function:

items=[(' name ', ' Test '), (' age ', 14)]

D=dict (items)

d[' name ']

Len (d) Returns the number of key-values in dictionary D

D[K] Returns the value associated to the key

D[k]=v to associate the value V to the K key

Del D[k] Delete item with key K

K in D determine if dictionary D contains key k

Example for:

people={' test1 ': {' phone ': 123, ' addr ': ' Beijing '}, ' test2:{' phone ', 12345, ' addr ': ' Tianjing '}}

people[' test1][' phone ']

Html= ""

<title>% (title) s</title>

<body>% (body) s</body>

‘‘‘

data={' head ': ' This was example ', ' title ': ' This is a example ', ' body ': ' Hello world! '}

Print Html%data

Clear: Clears all the entries in the dictionary, and can clear the other dictionaries of negative values at the same time, equivalent to recursive cleanup

Items.clear ()

Copy: Copies the dictionary, the original dictionary will not be affected when the value is replaced, but if a value is modified, the original

Dictionaries are affected (similar to deleting values in an item)

Deepcopy: Deep copy, copy modification does not affect the original dictionary

From copy import deepcopy

Items.deepcopy ()

Fromkeys: Creates a new dictionary with the given key, the default corresponding value for each key is None

{}.fromkeys ([' Name ', ' age '])

Get: Gets the value of the key in the dictionary, if there is no error

Items.get (' name ')

Has_key: Determine if the dictionary contains a corresponding key, similar to K in B, but there is no such function in python3.0.

A.has_key (' name ')

Items: Display the dictionary as a list

A.items ()

Iteritems: Similar to items, but returns an iterative object

B=a.iteritems ()

Keys: Displays the keys in the dictionary as a list

Iterkeys: Similar to keys, except that an iteration object is generated

Pop: Removes the value of the given key

A.pop (' name ')

Popitem: Randomly deleting items from a dictionary

A.popitem ()

SetDefault: You can set a default value for a key that has no value, and if a key has a value, it returns the corresponding key value.

A.setdefault (' name ', ' Test ')

Update: Updates the entries in the dictionary, if the old dictionary and the new dictionary are duplicated, the duplicate entries are overwritten

A.update (b)

Values: Returns the value in the dictionary as a list

A.values ()

Itervalues: Returns the iteration result of the value in the dictionary, which can be called

A.itervalues ()

Python Basics _ Learning Notes