Use of the Python format function

Reprinted from: http://www.cnblogs.com/kaituorensheng/p/5709970.html

Python since 2.6, a new format string function Str.format (), powerful, can replace the original%

Note : The following operating version is python2.7

mapping example
Grammar

by {} and: replace%

By location

>>> ' {0} was {1} '. Format (' Jihite ', ' 4 years old ') ' Jihite are 4 years old ' >>> ' {0} is {1} {0} '. Format (' Jihi Te ', ' 4 years old ') ' Jihite are 4 years old Jihite '

The Format function allows you to accept unlimited number of arguments, unlimited order

by keyword

>>> ' {name}:{age} '. Format (age=4,name= ' jihite ') ' jihite:4 ' >>> ' {name}:{age} '. Format (age=4,name= ' Jihite ', locate= ' Beijing ') ' Jihite:4 '

Use = To assign a value to a variable in format parentheses

Through object properties

>>> class Person: ...     def __init__ (self, Name, age): ...         Self.name,self.age = name, age ...     def __func__ (self): ...         Return "This guy is {self.name}, was {self.age} old". Format (self=self) ... >>> s =person (' Jihite ', 4) >>> s . __func__ () ' This guy is Jihite, was 4 old '

by subscript

>>> ' {0[0]} is {0[1]} years old! '. Format ([' Jihite ', 4]) ' Jihite is 4 years old! ' >>> ' {0} is {1} years old! '. Format (' Jihite ', 4) ' Jihite is 4 years old! '

is actually through the location

Format qualifier

Through {}: symbol

Fill and align

^<> are centered, left-aligned, right-aligned, followed by width

>>> ' {: >10} '. Format (' jihite ') '    jihite ' >>> ' {: <10} '. Format (' jihite ') ' Jihite    ' > >> ' {: ^10} '. Format (' jihite ') '  jihite  '

Accuracy and type F

Accuracy is often used in conjunction with F

>>> ' {:. 2f} '. Format (3.1415) ' 3.14 ' >>> ' {:. 4f} '. Format (3.1) ' 3.1000 '

In-process conversion

>>> ' {: b} '. Format (Ten) ' 1010 ' >>> ' {: o} '. Format (Ten) ' >>> ' {:d} '. Format (Ten) ' >> > ' {: x} '. Format (Ten) ' A '

where b o D x indicates two or eight, 16 or 16 binary respectively

Thousands separator

>>> ' {:,} '. Format (1000000) ' 1,000,000 '

>>> ' {:,} '. Format (100000.23433)
' 100,000.23433 '

>>> ' {:,} '. Format (' Abcedef ') Traceback (most recent call last):  File "<stdin>", line 1, in <module& Gt Valueerror:cannot specify ', ' with ' s '.



In particular, the accuracy and type of use is very convenient.

Use of the Python format function