isnumeric(), isdigit(), isdecimal()辨析

1. 用法说明

• isdecimal(): True: Unicode数字，全角数字(双字节)；False: 罗马数字，汉字数字,小数；Error: byte数字(单字节)

S.isdecimal() -> bool

• isdigit(): True: Unicode数字，byte数字(单字节)，全角数字(双字节); False: 汉字数字，罗马数字,小数；Error: 无

S.isdigit() -> bool

• isnumeric(): True: Unicode数字，全角数字(双字节)，罗马数字，汉字数字；False: 小数；Error: byte数字(单字节)

S.isnumeric() -> bool

代码示例

s = '123'
print(s.isdigit())  # output：True
print(s.isdecimal())  # output: True
print(s.isnumeric())  # output: True

s = b'123'
print(s.isdigit())    # output：True
print(s.isdecimal())  # output: error
print(s.isnumeric())  # output: error

s = '123.0'
print(s.isdigit())    # output: False
print(s.isdecimal())  # output: False
print(s.isnumeric())  # output: False

s = '三叁'
print(s.isdigit())    # output: False
print(s.isdecimal())  # output: False
print(s.isnumeric())  # output: True  神奇，汉字数字都可以识别

s = 'Ⅲ'
print(s.isdigit())    # output: Fasle
print(s.isdecimal())  # output: Fasle
print(s.isnumeric())  # output: True

s = '2a'
print(s.isdigit())    # output: False
print(s.isdecimal())  # output: False
print(s.isnumeric())  # output: False

Pandas代码示例：

import pandas as pd

df=pd.DataFrame({
'Score': [4.0,6,'3 1/3',7,'43a'],
'Foo': ['Nis','and stimpy','d','cab','abba'],
'Faggio':[0,1,0,1,0]
})
print(df)

df1 = df[df['Score'].str.isnumeric().isnull()]
print(df1)

df2 = df[df['Score'].str.isdigit().isnull()]
print(df2)

output:

Score	Foo	Faggio
0	4.0	Nis
1	6	and stimpy
2	3 1/3	d
3	7	cab
4	43a	abba

---

Score	Foo	Faggio
0	4.0	Nis
1	6	and stimpy
3	7	cab

---

Score	Foo	Faggio
0	4.0	Nis
1	6	and stimpy
3	7	cab