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LSST Data Management Base Package
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_schemaMapper.py
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1# This file is part of afw.
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
22__all__ = [] # import only for the side effects
23
25from lsst.utils import continueClass
26
27from ._schema import Field, Schema
28from ._table import SchemaMapper
29
30
31@continueClass
32class SchemaMapper: # noqa: F811
33
34 def addOutputField(self, field, type=None, doc=None, units="", size=None,
35 doReplace=False, parse_strict="raise"):
36 """Add an un-mapped field to the output Schema.
37
38 Parameters
39 ----------
40 field : `str` or `~lsst.afw.table.Field`
41 The string name of the `Field`, or a fully-constructed
42 `Field` object. If the latter, all other arguments
43 besides doReplace are ignored.
44 type : `str`
45 The type of field to create. Valid types are the keys of the
46 afw.table.Field dictionary.
47 doc : `str`
48 Documentation for the field.
49 unit : `str`
50 Units for the field, or an empty string if unitless.
51 size : `int`
52 Size of the field; valid for string and array fields only.
53 doReplace : `bool`
54 If a field with this name already exists, replace it instead of
55 raising pex.exceptions.InvalidParameterError.
56 parse_strict : `str`
57 One of 'raise' (default), 'warn', or 'strict', indicating how to
58 handle unrecognized unit strings. See also astropy.units.Unit.
59
60 Returns
61 -------
62 key : `~lsst.afw.table.Key`
63 The key of the field added.
64 """
65 if isinstance(field, str):
66 field = Field[type](field, doc=doc, units=units,
67 size=size, parse_strict=parse_strict)
68 return field._addTo(self.editOutputSchema(), doReplace)
69
70 def addMapping(self, input, output=None, doReplace=True):
71 """Add a mapped field to the output schema.
72
73 Parameters
74 ----------
75 input : `~lsst.afw.table.Key`
76 A `Key` from the input schema whose values will be mapped to the new
77 field.
78 output : `str` or `~lsst.afw.table.Field`
79 A `Field` object that describes the new field to be added to the
80 output schema, or the name of the field (with documentation and
81 units copied from the input schema). May be None to copy everything
82 from the input schema.
83 doReplace : `bool`
84 If a field with this name already exists in the output schema,
85 replace it instead of raising `pex.exceptions.InvalidParameterError`.
86
87 Returns
88 -------
89 key : `~lsst.afw.table.Key`
90 The key for the new mapped field.
91 """
92 # Workaround for calling positional arguments; avoids an API change during pybind11 conversion,
93 # but we should just make that change and encourage using kwargs in the
94 # future.
95 if output is True or output is False:
96 doReplace = output
97 output = None
98 return input._addMappingTo(self, output, doReplace)
99
100 def __eq__(self, other):
101 """SchemaMappers are equal if their respective input and output
102 schemas are identical, and they have the same mappings defined.
103
104 Note: It was simpler to implement equality in python than in C++.
105 """
106 iSchema = self.getInputSchema()
107 oSchema = self.getOutputSchema()
108 if (not (iSchema.compare(other.getInputSchema(), Schema.IDENTICAL) == Schema.IDENTICAL
109 and oSchema.compare(other.getOutputSchema(), Schema.IDENTICAL) == Schema.IDENTICAL)):
110 return False
111
112 for item in iSchema:
113 if self.isMapped(item.key) and other.isMapped(item.key):
114 if (self.getMapping(item.key) == other.getMapping(item.key)):
115 continue
116 else:
117 return False
118 elif (not self.isMapped(item.key)) and (not other.isMapped(item.key)):
119 continue
120 else:
121 return False
122
123 return True
124
125 def __reduce__(self):
126 """To support pickle."""
127 mappings = {}
128 for item in self.getInputSchema():
129 try:
130 key = self.getMapping(item.key)
132 # Not all fields may be mapped, so just continue if a mapping is not found.
133 continue
134 mappings[item.key] = self.getOutputSchema().find(key).field
135 return (makeSchemaMapper, (self.getInputSchema(), self.getOutputSchema(), mappings))
136
137
138def makeSchemaMapper(input, output, mappings):
139 """Build a mapper from two Schemas and the mapping between them.
140 For pickle support.
141
142 Parameters
143 ----------
144 input : `lsst.afw.table.Schema`
145 The input schema for the mapper.
146 output : `lsst.afw.table.Schema`
147 The output schema for the mapper.
148 mappings : `dict` [`lsst.afw.table.Key`, `lsst.afw.table.Key`]
149 The mappings to define between the input and output schema.
150
151 Returns
152 -------
153 mapper : `lsst.afw.table.SchemaMapper`
154 The constructed SchemaMapper.
155 """
156 mapper = SchemaMapper(input, output)
157 for key, value in mappings.items():
158 mapper.addMapping(key, value)
159 return mapper
addOutputField(self, field, type=None, doc=None, units="", size=None, doReplace=False, parse_strict="raise")
addMapping(self, input, output=None, doReplace=True)
Tag types used to declare specialized field types.
Definition misc.h:31
Reports attempts to access elements using an invalid key.
Definition Runtime.h:151
makeSchemaMapper(input, output, mappings)