问题

我需要确定一个字符串是一个普通整数，一个普通浮点数，一个使用 `e` 的浮点数，或者无法解析为数字。这是我想出的方法，但这感觉像是已经存在的东西，也许在numpy中？我对库和谷歌进行了简要的扫描，没有看到任何东西，这已经是一个事情了吗，只是我没有看到吗？

PLAIN_INT, PLAIN_FLOAT, E_FLOAT, STRING = range(4)

# 应该只是可选的 - 然后是数字
sample_plain_ints = ['1', '0', '-5', '333333333']
# 需要包含一个点
plain_floats = ['1.0', '-5.0', '-33.212', '0.0', '-1.', '-3.']
# 不需要包含一个点
e_floats = ['1.3e5', '-1.2e5', '0.0e0', '5e-3', '3e23', '3E5', '-3E-12']
# 其他
strings = ['aether', '1ee3', 'buzz', 'eeep', '121212beep']

def determine_str_type(item):
    try:
        float(item)
        try:
            int(item)
            return PLAIN_INT
        except ValueError:
            return E_FLOAT if 'E' in item.upper() else PLAIN_FLOAT
    except ValueError:
        return STRING

assert all([determine_str_type(item) == PLAIN_INT for item in sample_plain_ints])
assert all([determine_str_type(item) == PLAIN_FLOAT for item in plain_floats])
assert all([determine_str_type(item) == E_FLOAT for item in e_floats])
assert all([determine_str_type(item) == STRING for item in strings])

PLAIN_INT, PLAIN_FLOAT, E_FLOAT, STRING = range(4)

# should be just optionally - then numbers
sample_plain_ints = ['1', '0', '-5', '333333333']
# need to contain a dot
plain_floats = ['1.0', '-5.0', '-33.212', '0.0', '-1.', '-3.']
# do not need to contain a dot
e_floats = ['1.3e5', '-1.2e5', '0.0e0', '5e-3', '3e23', '3E5', '-3E-12']
# other
strings = ['aether', '1ee3', 'buzz', 'eeep', '121212beep']


def determine_str_type(item):
    try:
        float(item)
        try:
            int(item)
            return PLAIN_INT
        except ValueError:
            return E_FLOAT if 'E' in item.upper() else PLAIN_FLOAT
    except ValueError:
        return STRING


assert all([determine_str_type(item) == PLAIN_INT for item in sample_plain_ints])
assert all([determine_str_type(item) == PLAIN_FLOAT for item in plain_floats])
assert all([determine_str_type(item) == E_FLOAT for item in e_floats])
assert all([determine_str_type(item) == STRING for item in strings])

答案1

得分: 5

我会用正则表达式 (`(-?\d+)(\.\d*)?([eE]-?\d+)?$`) 来处理，捕获不同的部分，然后根据输出决定：

```python
import re

lst = ['1', '0', '-5', '333333333', '1.0', '-5.0', '-33.212', '0.0', '-1.', '-3.', '1.3e5', '-1.2e5', '0.0e0', '5e-3', '3e23', '3E5', '-3E-12', 'aether', '1ee3', 'buzz', 'eeep', '121212beep']

def determine_str_type(s):
    pat = re.compile(r'(-?\d+)(\.\d*)?([eE]-?\d+)?$')
    match m.groups() if (m:=pat.match(s)) else None:
        case None:
            return 'STRING '
        case (_, None, None):
            return 'PLAIN_INT'
        case (_, _, None):
            return 'PLAIN_FLOAT'
        case (_, _, _):
            return 'E_FLOAT'
        
for s in lst:
    print(f'{s: <11}: {determine_str_type(s)}')

输出：

1          : PLAIN_INT
0          : PLAIN_INT
-5         : PLAIN_INT
333333333  : PLAIN_INT
1.0        : PLAIN_FLOAT
-5.0       : PLAIN_FLOAT
-33.212    : PLAIN_FLOAT
0.0        : PLAIN_FLOAT
-1.        : PLAIN_FLOAT
-3.        : PLAIN_FLOAT
1.3e5      : E_FLOAT
-1.2e5     : E_FLOAT
0.0e0      : E_FLOAT
5e-3       : E_FLOAT
3e23       : E_FLOAT
3E5        : E_FLOAT
-3E-12     : E_FLOAT
aether     : STRING 
1ee3       : STRING 
buzz       : STRING 
eeep       : STRING 
121212beep : STRING 

正则表达式演示

<details>
<summary>英文:</summary>

I would use a regex for that (`(-?\d+)(\.\d*)?([eE]-?\d+)?$`), capture the different parts and decide depending on the output:

import re

lst = ['1', '0', '-5', '333333333', '1.0', '-5.0', '-33.212', '0.0', '-1.', '-3.', '1.3e5', '-1.2e5', '0.0e0', '5e-3', '3e23', '3E5', '-3E-12', 'aether', '1ee3', 'buzz', 'eeep', '121212beep']

def determine_str_type(s):
pat = re.compile(r'(-?\d+)(.\d*)?([eE]-?\d+)?$')
match m.groups() if (m:=pat.match(s)) else None:
case None:
return 'STRING '
case (, None, None):
return 'PLAIN_INT'
case (, , None):
return 'PLAIN_FLOAT'
case (, _, _):
return 'E_FLOAT'

for s in lst:
print(f'{s: <11}: {determine_str_type(s)}')

Output:

1 : PLAIN_INT
0 : PLAIN_INT
-5 : PLAIN_INT
333333333 : PLAIN_INT
1.0 : PLAIN_FLOAT
-5.0 : PLAIN_FLOAT
-33.212 : PLAIN_FLOAT
0.0 : PLAIN_FLOAT
-1. : PLAIN_FLOAT
-3. : PLAIN_FLOAT
1.3e5 : E_FLOAT
-1.2e5 : E_FLOAT
0.0e0 : E_FLOAT
5e-3 : E_FLOAT
3e23 : E_FLOAT
3E5 : E_FLOAT
-3E-12 : E_FLOAT
aether : STRING
1ee3 : STRING
buzz : STRING
eeep : STRING
121212beep : STRING

[regex demo](https://regex101.com/r/J41gmM/1)

</details>