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| from sympy.external import import_module | |
| from sympy.utilities.decorator import doctest_depends_on | |
| from sympy.parsing.latex.lark import LarkLaTeXParser, TransformToSymPyExpr, parse_latex_lark # noqa | |
| from .errors import LaTeXParsingError # noqa | |
| __doctest_requires__ = {('parse_latex',): ['antlr4', 'lark']} | |
| def parse_latex(s, strict=False, backend="antlr"): | |
| r"""Converts the input LaTeX string ``s`` to a SymPy ``Expr``. | |
| Parameters | |
| ========== | |
| s : str | |
| The LaTeX string to parse. In Python source containing LaTeX, | |
| *raw strings* (denoted with ``r"``, like this one) are preferred, | |
| as LaTeX makes liberal use of the ``\`` character, which would | |
| trigger escaping in normal Python strings. | |
| backend : str, optional | |
| Currently, there are two backends supported: ANTLR, and Lark. | |
| The default setting is to use the ANTLR backend, which can be | |
| changed to Lark if preferred. | |
| Use ``backend="antlr"`` for the ANTLR-based parser, and | |
| ``backend="lark"`` for the Lark-based parser. | |
| The ``backend`` option is case-sensitive, and must be in | |
| all lowercase. | |
| strict : bool, optional | |
| This option is only available with the ANTLR backend. | |
| If True, raise an exception if the string cannot be parsed as | |
| valid LaTeX. If False, try to recover gracefully from common | |
| mistakes. | |
| Examples | |
| ======== | |
| >>> from sympy.parsing.latex import parse_latex | |
| >>> expr = parse_latex(r"\frac {1 + \sqrt {\a}} {\b}") | |
| >>> expr | |
| (sqrt(a) + 1)/b | |
| >>> expr.evalf(4, subs=dict(a=5, b=2)) | |
| 1.618 | |
| >>> func = parse_latex(r"\int_1^\alpha \dfrac{\mathrm{d}t}{t}", backend="lark") | |
| >>> func.evalf(subs={"alpha": 2}) | |
| 0.693147180559945 | |
| """ | |
| if backend == "antlr": | |
| _latex = import_module( | |
| 'sympy.parsing.latex._parse_latex_antlr', | |
| import_kwargs={'fromlist': ['X']}) | |
| if _latex is not None: | |
| return _latex.parse_latex(s, strict) | |
| elif backend == "lark": | |
| return parse_latex_lark(s) | |
| else: | |
| raise NotImplementedError(f"Using the '{backend}' backend in the LaTeX" \ | |
| " parser is not supported.") | |