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Create Format String Syntax.py
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@lichangke
lichangke committed Apr 17, 2019
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#!/usr/bin/env python
# -*- encoding: utf-8 -*-
'''
@File : Format String Syntax.py
@Time : 2019/04/17 22:49:02
@Author : leacoder
@Version : 1.0
@Contact : leacock1991@gmail.com
@License :
@Desc :
python 3.7.3 标准库 string 常见的字符串操作
本文件包含：Format examples 字符串格式化示例
其他方法参见
https://docs.python.org/3/library/string.html#format-examples
'''

# here put the import lib

# 包含str.format（）语法的示例以及与旧的％-formatting的比较。
# 在大多数情况下，语法类似于旧的％-formatting，添加了{}和with：而不是％。例如，'％03.2f'可以翻译为'{：03.2f}'。


# 按位置访问参数：Accessing arguments by position:
tupdata = ("This","is","a","test") # 元组
formatstr = '{0} {1} {2} {3}'.format("This","is","a","test")
print(formatstr) # This is a test
formatstr = '{} {} {} {}'.format(*tupdata) # *data 解包参数序列
print(formatstr) # This is a test
formatstr = '{3} {2} {1} {0}'.format(*tupdata) # *data 解包参数序列
print(formatstr) # test a is This
formatstr = '{2} {3} {1} {2} {3}'.format(*tupdata) # 参数可以重复
print(formatstr) # a test is a test
# 按位置访问参数：Accessing arguments by position: End


# 按关键字访问参数：Accessing arguments by name：
dicdata = {'Author':'leacoder','Time':'2019/04/17'}
formatstr = 'The author is {Author}，The time is {Time}'.format(Author='leacoder',Time='2019/04/17')
print(formatstr) # The author is leacoder，The time is 2019/04/17
formatstr = 'The author is {Author}，The time is {Time}'.format(**dicdata)
print(formatstr) # The author is leacoder，The time is 2019/04/17
# 按关键字访问参数：Accessing arguments by name： End


# 访问参数的属性：Accessing arguments’ attributes:
class Point:
def __init__(self,x,y):
self.x ,self.y = x, y
point = Point(4,2)
formatstr = 'Thie point is ({key.x},{key.y})'.format(key = point) # key 可为其他
print(formatstr) # Thie point is (4,2)
formatstr = 'Thie point is ({point.x},{point.y})'.format(point = point) # point 可为其他
print(formatstr) # Thie point is (4,2)
# 访问参数的属性：Accessing arguments’ attributes: End


# 访问参数的各项：Accessing arguments’ items:
tupdata = ("leacoder","2019/04/17") # 元组
formatstr = 'The author is {0[0]},The time is {0[1]}'.format(tupdata)
print(formatstr) # The author is leacoder,The time is 2019/04/17
formatstr = 'The author is {0[0]},The time is {0[1]}'.format(*tupdata) # 注意区别
print(formatstr) # The author is l,The time is e
# 访问参数的各项：Accessing arguments’ items:End


# 替换％s和％r： Replacing %s and %r: 使用 !s !r
formatstr = "repr() shows quotes: {!r}; str() doesn't: {!s}".format('test1', 'test2')
print(formatstr) # repr() shows quotes: 'test1'; str() doesn't: test2
# 替换％s和％r： Replacing %s and %r: End

# 对齐文本并指定宽度：Aligning the text and specifying a width:
formatstr = '{:<30}'.format('left aligned') # 左对齐 30位
print(formatstr) # ‘left aligned ’ 为了体现位数加了‘’
formatstr = '{:>30}'.format('right aligned') # 右对齐 30位
print(formatstr) # ‘ right aligned’
formatstr = '{:^30}'.format('centered') # 中间对齐 30位
print(formatstr) # ‘ centered ’
formatstr = '{:*^30}'.format('centered') # 使用* 作为填充字符
print(formatstr) # ‘***********centered***********’
# 对齐文本并指定宽度：Aligning the text and specifying a width: End

# 替换％+ f，％ - f和％f并指定符号 Replacing %+f, %-f, and % f and specifying a sign:
formatstr = '{:+f}; {:+f}'.format(3.14, -3.14) # 总是显示它符号
print(formatstr) # ‘+3.140000; -3.140000’
formatstr = '{: f}; {: f}'.format(3.14, -3.14) # 正数前显示空格
print(formatstr) # ‘ 3.140000; -3.140000’
formatstr = '{:-f}; {:-f}'.format(3.14, -3.14) # 只显示负号 同 '{:f}; {:f}'
print(formatstr) # ‘3.140000; -3.140000’
# 替换％+ f，％ - f和％f并指定符号 Replacing %+f, %-f, and % f and specifying a sign: End



# 替换％x和％o并将值转换为不同的进制：Replacing %x and %o and converting the value to different bases:
formatstr = "int: {0:d}; hex: {0:x}; oct: {0:o}; bin: {0:b}".format(64)
print(formatstr) # int: 64; hex: 40; oct: 100; bin: 1000000
formatstr = "int: {0:d}; hex: {0:#x}; oct: {0:#o}; bin: {0:#b}".format(64)
print(formatstr) # int: 64; hex: 0x40; oct: 0o100; bin: 0b1000000
formatstr = "int: {0:d}; hex: {0:#x}; oct: {0:#o}; bin: {0:#b}".format(0b1000001) # 也支持其他进制
print(formatstr) # int: 65; hex: 0x41; oct: 0o101; bin: 0b1000001
# 替换％x和％o并将值转换为不同的进制：Replacing %x and %o and converting the value to different bases: End


# 使用逗号作为千位分隔符： Using the comma as a thousands separator:
formatstr = '{:,}'.format(1234567890)
print(formatstr) # 1,234,567,890
# 使用逗号作为千位分隔符： Using the comma as a thousands separator: End



# 表达百分比：Expressing a percentage:
points = 1
total = 3
formatstr = 'points / total = {:.2%}'.format(points/total)
print(formatstr) # points / total = 33.33%
# 表达百分比：Expressing a percentage: End



# 使用特定类型的格式：Using type-specific formatting:
import datetime
d = datetime.datetime(2019, 4, 17, 22, 49, 2) # 2019/04/17 22:49:02
formatstr = '{:%Y-%m-%d %H:%M:%S}'.format(d)
print(formatstr) # 2019-04-17 22:49:02
# 使用特定类型的格式：Using type-specific formatting: End

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