Python----format

1/cmd command under Python Development Mode Exit method: Ctrl + Z

2/natural string preceded by the string R, for example R "hello/n", you can retain the escape character

3/String Repeat *n

4/SUBSTRING: index, slice

5. Set: Establish relationship (& intersection, | Set,-difference set), remove duplicate elements

6. Pickle Pickling Purpose: Data is serialized, stored in memory, and persisted locally

Methods: 1, pickle module: Dumps function to serialize data, loads function to restore data, the data type is restored

2, stored in the third file serialization, dump function to store objects in the file

F1=file (' 1.PK1 ', ' WB ')
Pickle.dump (Object,file,true)

The load function restores the data stored in the file

F2=file (' 1.pk1 ', ' RB ')
T=pickle.load (F2)

7,//Divide the whole number of parts

* * Exponentiation operation

~ Bitwise rollover ~a=-(A+1)

The following transfers from http://www.jb51.net/article/63672.htm

The function Str.format () that formats the string,

Grammar

It replaces% with {} and:.
Map sample

By location

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123456

In [1]: ‘{0},{1}‘.format(‘kzc‘,18) Out[1]: ‘kzc,18‘ In [2]: ‘{},{}‘.format(‘kzc‘,18) Out[2]: ‘kzc,18‘ In [3]: ‘{1},{0},{1}‘.format(‘kzc‘,18) Out[3]: ‘18,kzc,18‘

The Format function of the string can accept an unlimited number of parameters, the position can be out of order, can not be used or multiple times, but 2.6 can not be empty {},2.7.
by keyword parameter

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12	In [5]: ‘{name},{age}‘.format(age=18,name=‘kzc‘) Out[5]: ‘kzc,18‘

Through object properties

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12345

class Person: def __init__(self,name,age): self.name,self.age = name,age def __str__(self): return ‘This guy is {self.name},is {self.age} old‘.format(self=self)

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12	In [2]: str(Person(‘kzc‘,18)) Out[2]: ‘This guy is kzc,is 18 old‘

by subscript

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123	In [7]: p=[‘kzc‘,18] In [8]: ‘{0[0]},{0[1]}‘.format(p) Out[8]: ‘kzc,18‘

With these convenient "mapping" methods, we have a lazy weapon. Basic Python knowledge tells us that list and tuple can be "broken" into normal parameters to the function, and dict can be broken into the keyword parameters to the function (through and *). So you can easily pass a list/tuple/dict to the Format function. Very flexible.
Format qualifier

It has a rich "format qualifier" (syntax is {} with:), such as:

Fill and align
Padding is used in conjunction with alignment
^, <, > center, Align Left, right, back with width
: The fill character after the number, only one character, not specified by default is filled with a space
Like what

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123456

In [15]: ‘{:>8}‘.format(‘189‘) Out[15]: ‘ 189‘In [16]: ‘{:0>8}‘.format(‘189‘) Out[16]: ‘00000189‘In [17]: ‘{:a>8}‘.format(‘189‘) Out[17]: ‘aaaaa189‘

Accuracy and type F
Accuracy is often used in conjunction with Type F

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12	In [44]: ‘{:.2f}‘.format(321.33345) Out[44]: ‘321.33‘

Where. 2 represents a precision of 2 length, and F represents a float type.

Other types
Mainly in the system, B, D, O, X are binary, decimal, octal, hexadecimal.

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12345678

In [54]: ‘{:b}‘.format(17) Out[54]: ‘10001‘In [55]: ‘{:d}‘.format(17) Out[55]: ‘17‘In [56]: ‘{:o}‘.format(17) Out[56]: ‘21‘In [57]: ‘{:x}‘.format(17) Out[57]: ‘11‘

Use, the number can also be used to make the amount of thousands separator.

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12	In [47]: ‘{:,}‘.format(1234567890) Out[47]: ‘1,234,567,890‘

Python----format