Python格式化输出

一、百分号格式化（%）

1.整型输出%d

'my age is %d'% (26)

2.输出字符串%s

'my name is %s' % 'xiaoming'
# 'my name is xiaoming'

3.输出浮点数%f

'His height is %f m' % 1.890
# 'His height is 1.890000 m'

4.保留2位小数

'His height is %.2f m' % (1.890)
# 'His height is 1.89 m'

5.指定占位符宽度（右对齐）

'name:%10s,age:%10d,height:%5.2f' % ('xiaoming',26,1.890)
# 'name:  xiaoming,age:        26,height: 1.89'

6.指定占位符宽度（左对齐）

'name:%-10s,age:%-10d,height:%-5.2f' % ('xiaoming',26,1.890)
# 'name:xiaoming  ,age:26        ,height:1.89 '

7.字符串截取

%.2s表示截取前两位字符串

%10.2s表示10个占位符，截取前两位字符串

'%.2s' % 'hello word'
# 'he'

'%10.2s' % 'hello word'
# '        he'

8、输出%

'今年GDP的增长率:%d%%' % 7
# '今年GDP的增长率:7%'

二、format格式化

1、不设置指定位置，按默认顺序

"{} {}".format("hello", "world")
# 'hello world'

2、指定位置

"{0} {1}".format("hello", "world")
# 'hello world'

3、指定多个位置

"{1} {0} {1}".format("hello", "world")
# 'world hello world'

4、指定变量名传参

"name: {name}, age: {age}".format(name="小新", age=13)
# 'name: 小新, age: 13'

5、元组传参

infos = '钢铁侠', 66, '小辣椒'
'我是{}，身价{}亿'.format(*infos)
# '我是钢铁侠，身价66亿'

6、列表传参

my_list = ['python', 'short']
'hello {0[0]}, life is {0[1]}'.format(my_list)
# hello python，life is short

7、字典传参

venom = {'name': '毒液', 'weakness': '火'}
'我是{name}，我怕{weakness}'.format(**venom)
# '我是毒液，我怕火'

8、类传参

class AssignValue:

    def __init__(self, value):
        self.value = value

my_value = AssignValue(6)
'value 为: {0.value}'.format(my_value)
# 'value 为: 6'

9.字典转元组传参

venom = {'name': '毒液', 'weakness': '火'}
tup = tuple(venom.values())
'我是{}，我怕{}'.format(*tup)

10、数字格式化

保留两位小数

"{:.2f}".format(3.1415926)  # '3.14'

带符号保留小数点后两位

"{:+.2f}".format(3.1415926)  # '+3.14'

不带小数

"{:.0f}".format(3.1415926)  # '3'

数字补零 (填充左边, 宽度为2)

"{:0>2d}".format(5)  # '05'

数字补x (填充右边, 宽度为4)

"{:x<4d}".format(10)  # '10xx'

百分比格式，保留两位小数

"{:.2%}".format(0.25)  # '25.00%'

以逗号分隔数字

"{:,}".format(1000000)  # '1,000,000'

三、python3.6新特性f""

f"hello {'python'}, i {'love'} python"
# 'hello python, i love python'

name = '蜡笔小新'
age = 5
f"my name is {name}, age is {age}"
# 'my name is 蜡笔小新, age is 5'