PySR / pysr /export_numpy.py
MilesCranmer's picture
fix: boolean selection masks in pandas eval
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"""Code for exporting discovered expressions to numpy"""
import warnings
from typing import List, Union
import numpy as np
import pandas as pd
from numpy.typing import NDArray
from sympy import Expr, Symbol, lambdify
def sympy2numpy(eqn, sympy_symbols, *, selection=None):
return CallableEquation(eqn, sympy_symbols, selection=selection)
class CallableEquation:
"""Simple wrapper for numpy lambda functions built with sympy"""
_sympy: Expr
_sympy_symbols: List[Symbol]
_selection: Union[NDArray[np.bool_], None]
def __init__(self, eqn, sympy_symbols, selection=None):
self._sympy = eqn
self._sympy_symbols = sympy_symbols
self._selection = selection
def __repr__(self):
return f"PySRFunction(X=>{self._sympy})"
def __call__(self, X):
expected_shape = (X.shape[0],)
if isinstance(X, pd.DataFrame):
# Lambda function takes as argument:
return self._lambda(
**{k: X[k].values for k in map(str, self._sympy_symbols)}
) * np.ones(expected_shape)
if self._selection is not None:
if X.shape[1] != self._selection.sum():
warnings.warn(
"`X` should be of shape (n_samples, len(self._selection)). "
"Automatically filtering `X` to selection. "
"Note: Filtered `X` column order may not match column order in fit "
"this may lead to incorrect predictions and other errors."
)
X = X[:, self._selection]
return self._lambda(*X.T) * np.ones(expected_shape)
@property
def _lambda(self):
return lambdify(self._sympy_symbols, self._sympy)