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1# This file is part of pipe_tasks. 

2# 

3# Developed for the LSST Data Management System. 

4# This product includes software developed by the LSST Project 

5# (https://www.lsst.org). 

6# See the COPYRIGHT file at the top-level directory of this distribution 

7# for details of code ownership. 

8# 

9# This program is free software: you can redistribute it and/or modify 

10# it under the terms of the GNU General Public License as published by 

11# the Free Software Foundation, either version 3 of the License, or 

12# (at your option) any later version. 

13# 

14# This program is distributed in the hope that it will be useful, 

15# but WITHOUT ANY WARRANTY; without even the implied warranty of 

16# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 

17# GNU General Public License for more details. 

18# 

19# You should have received a copy of the GNU General Public License 

20# along with this program. If not, see <https://www.gnu.org/licenses/>. 

21 

22from __future__ import annotations 

23 

24__all__ = ("makeColumnExpressionAction", ) 

25 

26import ast 

27import operator as op 

28 

29from typing import Mapping, MutableMapping, Set, Type, Union, Optional, Any, Iterable 

30 

31from numpy import log10 as log 

32from numpy import (cos, sin, cosh, sinh) 

33import pandas as pd 

34 

35from ..configurableActions import ConfigurableActionField 

36from ._baseDataFrameActions import DataFrameAction 

37 

38 

39OPERATORS = {ast.Add: op.add, ast.Sub: op.sub, ast.Mult: op.mul, 

40 ast.Div: op.truediv, ast.Pow: op.pow, ast.BitXor: op.xor, 

41 ast.USub: op.neg} 

42 

43EXTRA_MATH = {"cos": cos, "sin": sin, "cosh": cosh, "sinh": sinh, "log": log} 

44 

45 

46class ExpressionParser(ast.NodeVisitor): 

47 def __init__(self, **kwargs): 

48 self.variables = kwargs 

49 self.variables['log'] = log 

50 

51 def visit_Name(self, node): 

52 if node.id in self.variables: 

53 return self.variables[node.id] 

54 else: 

55 return None 

56 

57 def visit_Num(self, node): 

58 return node.n 

59 

60 def visit_NameConstant(self, node): 

61 return node.value 

62 

63 def visit_UnaryOp(self, node): 

64 val = self.visit(node.operand) 

65 return OPERATORS[type(node.op)](val) 

66 

67 def visit_BinOp(self, node): 

68 lhs = self.visit(node.left) 

69 rhs = self.visit(node.right) 

70 return OPERATORS[type(node.op)](lhs, rhs) 

71 

72 def visit_Call(self, node): 

73 if node.func.id in self.variables: 

74 function = self.visit(node.func) 

75 return function(self.visit(node.args[0])) 

76 else: 

77 raise ValueError("String not recognized") 

78 

79 def generic_visit(self, node): 

80 raise ValueError("String not recognized") 

81 

82 

83def makeColumnExpressionAction(className: str, expr: str, 

84 exprDefaults: Optional[Mapping[str, Union[DataFrameAction, 

85 Type[DataFrameAction]]]] = None, 

86 docstring: str = None 

87 ) -> Type[DataFrameAction]: 

88 node = ast.parse(expr, mode='eval') 

89 

90 # gather the specified names 

91 names: Set[str] = set() 

92 for elm in ast.walk(node): 

93 if isinstance(elm, ast.Name): 

94 names.add(elm.id) 

95 

96 # remove the known Math names 

97 names -= EXTRA_MATH.keys() 

98 

99 fields: Mapping[str, ConfigurableActionField] = {} 

100 for name in names: 

101 if exprDefaults is not None and (value := exprDefaults.get(name)) is not None: 101 ↛ 104line 101 didn't jump to line 104, because the condition on line 101 was never false

102 kwargs = {"default": value} 

103 else: 

104 kwargs = {} 

105 fields[name] = ConfigurableActionField(doc=f"expression action {name}", **kwargs) 

106 

107 # skip flake8 on N807 because this is a stand alone function, but it is 

108 # intended to be patched in as a method on a dynamically generated class 

109 def __call__(self, df: pd.DataFrame, **kwargs) -> pd.Series: # noqa: N807 

110 values_map = {} 

111 for name in fields: 

112 values_map[name] = getattr(self, name)(df, **kwargs) 

113 

114 parser = ExpressionParser(**values_map) 

115 return parser.visit(node.body) 

116 

117 # create the function to look up the columns for the dynamically created action 

118 def columns(self) -> Iterable[str]: 

119 for name in fields: 

120 yield from getattr(self, name).columns 

121 

122 dct: MutableMapping[str, Any] = {"__call__": __call__, "columns": property(columns)} 

123 if docstring is not None: 123 ↛ 125line 123 didn't jump to line 125, because the condition on line 123 was never false

124 dct['__doc__'] = docstring 

125 dct.update(**fields) 

126 

127 return type(className, (DataFrameAction, ), dct)