Python 鲜为人知的数值格式化

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大家在工作的时候经常用到的字符格式化，今天就总结一下

Python

Last login: Wed Jan 9 10:06:43 on ttys000 ➜ ~ ipython3 微信公众号：zeropython Python 3.6.8 |Anaconda, Inc.| (default, Dec 29 2018, 19:04:46) Type 'copyright', 'credits' or 'license' for more information IPython 6.4.0 -- An enhanced Interactive Python. Type '?' for help. In [1]: a = 123 In [2]: b = 1234567890.123456 In [3]: c = -123456.654321 In [4]: type(a) Out[4]: int In [5]: type(b) Out[5]: float In [9]: "数值{}".format(a) Out[9]: '数值123' In [10]: "数值{}".format(b) Out[10]: '数值1234567890.123456' # 新增 In [11]: f"数值{a}" Out[11]: '数值123' In [9]: "数值{}".format(a) Out[9]: '数值123' In [10]: "数值{}".format(b) Out[10]: '数值1234567890.123456' In [11]: f"数值{a}" Out[11]: '数值123' In [12]: f"数值{b}" Out[12]: '数值1234567890.123456' In [13]: # 以浮点型的方式显示呢 In [14]: f"数值{a:f}" Out[14]: '数值123.000000' In [15]: "数值{:f}".format(a) Out[15]: '数值123.000000' In [16]: # 正负数显示，整数只能显示整数，负数只显示负数 In [17]: "数值{:+f}".format(a) Out[17]: '数值+123.000000' In [18]: "数值{:-f}".format(a) Out[18]: '数值123.000000' In [19]: "数值{:+f}".format(c) Out[19]: '数值-123456.654321' In [20]: a Out[20]: 123 In [21]: b Out[21]: 1234567890.123456 # 如果想三位显示一个逗号进行区分直接在第二个f前面加, In [23]: f"数值{b:,f}" Out[23]: '数值1,234,567,890.123456' # 如果设置保留精度呢？ # .2f 就表示保留两位小数，保留规则为四舍五入 In [26]: f"数值{b:,.2f}" Out[26]: '数值1,234,567,890.12' In [27]: f"数值{b:,.3f}" Out[27]: '数值1,234,567,890.123' In [28]: f"数值{b:,.4f}" Out[28]: '数值1,234,567,890.1235' In [29]: # 如果想以百分比显示呢？ In [30]: In [30]: x = 10 In [31]: y = 3 In [35]: "百分比{:.2%}".format(x/y) Out[35]: '百分比333.33%'

Last login : Wed Jan 9 10 : 06 : 43 on ttys000

➜ ~ ipython3 微信公众号： zeropython

Python 3.6.8 | Anaconda , Inc . | ( default , Dec 29 2018 , 19 : 04 : 46 )

Type 'copyright' , 'credits' or 'license' for more information

IPython 6.4.0 -- An enhanced Interactive Python . Type '?' for help .

In [ 1 ] : a = 123

In [ 2 ] : b = 1234567890.123456

In [ 3 ] : c = - 123456.654321

In [ 4 ] : type ( a )

Out [ 4 ] : int

In [ 5 ] : type ( b )

Out [ 5 ] : float

In [ 9 ] : "数值{}" . format ( a )

Out [ 9 ] : '数值123'

In [ 10 ] : "数值{}" . format ( b )

Out [ 10 ] : '数值1234567890.123456'

# 新增

In [ 11 ] : f "数值{a}"

Out [ 11 ] : '数值123'

In [ 9 ] : "数值{}" . format ( a )

Out [ 9 ] : '数值123'

In [ 10 ] : "数值{}" . format ( b )

Out [ 10 ] : '数值1234567890.123456'

In [ 11 ] : f "数值{a}"

Out [ 11 ] : '数值123'

In [ 12 ] : f "数值{b}"

Out [ 12 ] : '数值1234567890.123456'

In [ 13 ] : # 以浮点型的方式显示呢

In [ 14 ] : f "数值{a:f}"

Out [ 14 ] : '数值123.000000'

In [ 15 ] : "数值{:f}" . format ( a )

Out [ 15 ] : '数值123.000000'

In [ 16 ] : # 正负数显示，整数只能显示整数，负数只显示负数

In [ 17 ] : "数值{:+f}" . format ( a )

Out [ 17 ] : '数值+123.000000'

In [ 18 ] : "数值{:-f}" . format ( a )

Out [ 18 ] : '数值123.000000'

In [ 19 ] : "数值{:+f}" . format ( c )

Out [ 19 ] : '数值-123456.654321'

In [ 20 ] : a

Out [ 20 ] : 123

In [ 21 ] : b

Out [ 21 ] : 1234567890.123456

# 如果想三位显示一个逗号进行区分直接在第二个f前面加,

In [ 23 ] : f "数值{b:,f}"

Out [ 23 ] : '数值1,234,567,890.123456'

# 如果设置保留精度呢？

# .2f 就表示保留两位小数，保留规则为四舍五入

In [ 26 ] : f "数值{b:,.2f}"

Out [ 26 ] : '数值1,234,567,890.12'

In [ 27 ] : f "数值{b:,.3f}"

Out [ 27 ] : '数值1,234,567,890.123'

In [ 28 ] : f "数值{b:,.4f}"

Out [ 28 ] : '数值1,234,567,890.1235'

In [ 29 ] : # 如果想以百分比显示呢？

In [ 30 ] :

In [ 30 ] : x = 10

In [ 31 ] : y = 3

In [ 35 ] : "百分比{:.2%}" . format ( x / y )

Out [ 35 ] : '百分比333.33%'

math 模块中的向上取值 ceil{天花板} 向下取值floor{地板}

Python

In [37]: b Out[37]: 1234567890.123456 In [38]: c Out[38]: -123456.654321 In [39]: import math In [40]: math.trunc(b) Out[40]: 1234567890 In [41]: math.trunc(c) Out[41]: -123456 In [42]: # 只截取整数不牵扯四舍五入 In [43]: In [43]: math.floor(b) Out[43]: 1234567890 In [44]: # 向下取数 In [45]: In [45]: math.ceil(123.0) Out[45]: 123 In [46]: math.ceil(123.1) Out[46]: 124 In [47]: # ceil 向上取数 In [48]: In [48]: # 平时我用内建函数

In [ 37 ] : b

Out [ 37 ] : 1234567890.123456

In [ 38 ] : c

Out [ 38 ] : - 123456.654321

In [ 39 ] : import math

In [ 40 ] : math . trunc ( b )

Out [ 40 ] : 1234567890

In [ 41 ] : math . trunc ( c )

Out [ 41 ] : - 123456

In [ 42 ] : # 只截取整数不牵扯四舍五入

In [ 43 ] :

In [ 43 ] : math . floor ( b )

Out [ 43 ] : 1234567890

In [ 44 ] : # 向下取数

In [ 45 ] :

In [ 45 ] : math . ceil ( 123.0 )

Out [ 45 ] : 123

In [ 46 ] : math . ceil ( 123.1 )

Out [ 46 ] : 124

In [ 47 ] : # ceil 向上取数

In [ 48 ] :

In [ 48 ] : # 平时我用内建函数

平时我用内建函数 ,参数第一个数值，第二个是要保留的位数支持四舍五入

Python

<br />In [49]: #round In [50]: round(b,1) Out[50]: 1234567890.1 In [51]: round(b,2) Out[51]: 1234567890.12 In [52]: round(b,4) Out[52]: 1234567890.1235 In [53]: # 参数第一个数值，第二个是要保留的位数支持四舍五入