如何在Sympy解析器中使用限制和积分

Question

我想知道如何评估Sympy Parser中的操作方程（ sympy.Series.limit函数），例如root，limit或积分。

from sympy.parsing.sympy_parser import parse_expr
temp = parse_expr("limit(1/x, x, 0, +)", transformations='all')

    Traceback (most recent call last):
  File "c:\Users\asdf\AppData\Local\Programs\Python\Python310\Lib\site-packages\data_manage\test.py", line 70, in <module>    parse = parse_expr("limit(1/x, x, 0, +)", transformations='all')
  File "C:\Users\asdf\AppData\Local\Programs\Python\Python310\lib\site-packages\sympy\parsing\sympy_parser.py", line 1105, in parse_expr
    raise e from ValueError(f"Error from parse_expr with transformed code: {code!r}")
  File "C:\Users\asdf\AppData\Local\Programs\Python\Python310\lib\site-packages\sympy\parsing\sympy_parser.py", line 1096, in parse_expr
    rv = eval_expr(code, local_dict, global_dict)
  File "C:\Users\asdf\AppData\Local\Programs\Python\Python310\lib\site-packages\sympy\parsing\sympy_parser.py", line 915, 
in eval_expr
    expr = eval(
  File "<string>", line 1
    limit (Integer (1 )/Symbol ('x' ),Symbol ('x' ),Integer (0 ),+)
                                                                  ^
SyntaxError: invalid syntax

Answer 1

您需要将极限方向包裹到字符串文字中：

temp = parse_expr("limit(1/x, x, 0, '+')", transformations='all')