Utilities for dealing with expressions¶

Parser¶

pymbolic.parse(expr_str)¶: Return a pymbolic.primitives.Expression tree corresponding to expr_str.

The parser is also relatively easy to extend. See the source code of the following class.

class pymbolic.parser.Parser¶

Compiler¶

class pymbolic.compiler.CompiledExpression(expression, variables=[])¶

This class encapsulates an expression compiled into Python bytecode for faster evaluation.

Its instances (unlike plain lambdas) are pickleable.

__call__(*args)¶

Interoperability with other symbolic systems¶

Interoperability with `sympy`¶

class pymbolic.interop.sympy.SympyToPymbolicMapper¶

__call__(expr)¶

class pymbolic.interop.sympy.PymbolicToSympyMapper¶

__call__(expr)¶

Interoperability with Maxima¶

class pymbolic.interop.maxima.MaximaStringifyMapper¶

class pymbolic.interop.maxima.MaximaParser¶

class pymbolic.interop.maxima.MaximaKernel(executable='maxima', timeout=30)¶

restart()¶

shutdown()¶

reset()¶

exec_str(s, enforce_prompt_numbering=True)¶

eval_str(s, enforce_prompt_numbering=True)¶

eval_expr(expr)¶

pymbolic.interop.maxima.eval_expr_with_setup(assignments, expr)¶

pymbolic.interop.maxima.diff(expr, var, count=1, assignments=())¶

Interoperability with Python’s `ast` module¶

An example:

src = """
def f():
    xx = 3*y + z * (12 if x < 13 else 13)
    yy = f(x, y=y)
"""

import ast
mod = ast.parse(src.replace("\n    ", "\n"))

print(ast.dump(mod))

from pymbolic.interop.ast import ASTToPymbolic
ast2p = ASTToPymbolic()

for f in mod.body:
    if not isinstance(f, ast.FunctionDef):
        continue

    for stmt in f.body:
        if not isinstance(stmt, ast.Assign):
            continue

        lhs, = stmt.targets
        lhs = ast2p(lhs)
        rhs = ast2p(stmt.value)

        print(lhs, rhs)

class pymbolic.interop.ast.ASTToPymbolic¶