Source code for sdv.metadata.dataset

"""Dataset Metadata class."""

import copy
import json
import logging
import os
from collections import defaultdict

import numpy as np
import pandas as pd

from sdv.constraints import Constraint
from sdv.metadata import visualization
from sdv.metadata.errors import MetadataError

LOGGER = logging.getLogger(__name__)

def _read_csv_dtypes(table_meta):
    """Get the dtypes specification that needs to be passed to read_csv."""
    dtypes = dict()
    for name, field in table_meta['fields'].items():
        field_type = field['type']
        if field_type == 'id' and field.get('subtype', 'integer') == 'string':
            dtypes[name] = str

    return dtypes

def _parse_dtypes(data, table_meta):
    """Convert the data columns to the right dtype after loading the CSV."""
    for name, field in table_meta['fields'].items():
        field_type = field['type']
        if field_type == 'datetime':
            datetime_format = field.get('format')
            data[name] = pd.to_datetime(data[name], format=datetime_format, exact=False)
        elif field_type == 'numerical' and field.get('subtype') == 'integer':
            data[name] = data[name].dropna().astype(np.int64)
        elif field_type == 'id' and field.get('subtype', 'integer') == 'integer':
            data[name] = data[name].dropna().astype(np.int64)

    return data

def _load_csv(root_path, table_meta):
    """Load a CSV with the right dtypes and then parse the columns."""
    relative_path = os.path.join(root_path, table_meta['path'])
    dtypes = _read_csv_dtypes(table_meta)

    data = pd.read_csv(relative_path, dtype=dtypes)
    data = _parse_dtypes(data, table_meta)

    return data

[docs]class Metadata: """Dataset Metadata. The Metadata class provides a unified layer of abstraction over the dataset metadata, which includes both the necessary details to load the data from the hdd and to know how to parse and transform it to numerical data. Args: metadata (str or dict): Path to a ``json`` file that contains the metadata or a ``dict`` representation of ``metadata`` following the same structure. root_path (str): The path to which the paths found inside the metadata are relative. If not given, it defaults to the folder where the metadata is located, or to None, if no metadata is given. """ _child_map = None _metadata = None _parent_map = None root_path = None _FIELD_TEMPLATES = { 'i': { 'type': 'numerical', 'subtype': 'integer', }, 'f': { 'type': 'numerical', 'subtype': 'float', }, 'O': { 'type': 'categorical', }, 'b': { 'type': 'boolean', }, 'M': { 'type': 'datetime', } } _DTYPES = { ('categorical', None): 'object', ('boolean', None): 'bool', ('numerical', None): 'float', ('numerical', 'float'): 'float', ('numerical', 'integer'): 'int', ('datetime', None): 'datetime64', ('id', None): 'int', ('id', 'integer'): 'int', ('id', 'string'): 'str' } def _analyze_relationships(self): """Extract information about child-parent relationships. Creates the following attributes: * ``_child_map``: set of child tables that each table has. * ``_parent_map``: set ot parents that each table has. """ self._child_map = defaultdict(set) self._parent_map = defaultdict(set) for table, table_meta in self._metadata['tables'].items(): if table_meta.get('use', True): for field_meta in table_meta['fields'].values(): ref = field_meta.get('ref') if ref: parent = ref['table'] self._child_map[parent].add(table) self._parent_map[table].add(parent) @staticmethod def _dict_metadata(metadata): """Get a metadata ``dict`` with SDV format. For each table create a dict of fields from a previous list of fields. Args: metadata (dict): Original metadata to format. Returns: dict: Formated metadata dict. """ new_metadata = copy.deepcopy(metadata) tables = new_metadata['tables'] if isinstance(tables, dict): new_metadata['tables'] = { table: meta for table, meta in tables.items() if meta.pop('use', True) } return new_metadata new_tables = dict() for table in tables: if table.pop('use', True): new_tables[table.pop('name')] = table fields = table['fields'] new_fields = dict() for field in fields: new_fields[field.pop('name')] = field table['fields'] = new_fields new_metadata['tables'] = new_tables return new_metadata
[docs] def __init__(self, metadata=None, root_path=None): if isinstance(metadata, str): self.root_path = root_path or os.path.dirname(metadata) with open(metadata) as metadata_file: metadata = json.load(metadata_file) else: self.root_path = root_path or '.' if metadata is not None: self._metadata = self._dict_metadata(metadata) else: self._metadata = {'tables': {}} self._analyze_relationships()
[docs] def get_children(self, table_name): """Get tables for which the given table is parent. Args: table_name (str): Name of the table from which to get the children. Returns: set: Set of children for the given table. """ return self._child_map[table_name]
[docs] def get_parents(self, table_name): """Get tables for with the given table is child. Args: table_name (str): Name of the table from which to get the parents. Returns: set: Set of parents for the given table. """ return self._parent_map[table_name]
[docs] def get_table_meta(self, table_name): """Get the metadata dict for a table. Args: table_name (str): Name of table to get data for. Returns: dict: table metadata Raises: ValueError: If table does not exist in this metadata. """ table = self._metadata['tables'].get(table_name) if table is None: raise ValueError('Table "{}" does not exist'.format(table_name)) return copy.deepcopy(table)
[docs] def get_tables(self): """Get the list with the tables found in this metadata. Returns: list: table names. """ return list(self._metadata['tables'].keys())
[docs] def get_field_meta(self, table_name, field_name): """Get the metadata dict for a table. Args: table_name (str): Name of the table to which the field belongs. field_name (str): Name of the field to get data for. Returns: dict: field metadata Raises: ValueError: If the table or the field do not exist in this metadata. """ field_meta = self.get_fields(table_name).get(field_name) if field_meta is None: raise ValueError( 'Table "{}" does not contain a field name "{}"'.format(table_name, field_name)) return copy.deepcopy(field_meta)
[docs] def get_fields(self, table_name): """Get the metadata of the fields of the indicated table. Args: table_name (str): Name of the table to get the fields from. Returns: dict: Mapping of field names and their metadata dicts. Raises: ValueError: If table does not exist in this metadata. """ return self.get_table_meta(table_name)['fields']
[docs] def get_primary_key(self, table_name): """Get the name of the primary key of the indicated table, if it has one. Args: table_name (str): Name of table for which to get the primary key field. Returns: str or None: Primary key field name. ``None`` if the table has no primary key. Raises: ValueError: If table does not exist in this metadata. """ return self.get_table_meta(table_name).get('primary_key')
[docs] def get_foreign_keys(self, parent, child): """Get the name of all the fields in the child that are foreign keys to this parent. If there is no relationship between the two tables an empty list is returned. Args: parent (str): Name of the parent table. child (str): Name of the child table. Returns: list[str]: List of foreign key names. """ foreign_keys = [] for name, field in self.get_fields(child).items(): ref = field.get('ref') if ref and ref['table'] == parent: foreign_keys.append(name) return foreign_keys
[docs] def load_table(self, table_name): """Load the data of the indicated table as a DataFrame. Args: table_name (str): Name of the table to load. Returns: pandas.DataFrame: DataFrame with the contents of the table. Raises: ValueError: If table does not exist in this metadata. """'Loading table %s', table_name) table_meta = self.get_table_meta(table_name) return _load_csv(self.root_path, table_meta)
[docs] def load_tables(self, tables=None): """Get a dictionary with data from multiple tables. If a ``tables`` list is given, only load the indicated tables. Otherwise, load all the tables from this metadata. Args: tables (list): List of table names. Defaults to ``None``. Returns: dict(str, pandasd.DataFrame): mapping of table names and their data loaded as ``pandas.DataFrame`` instances. """ return { table_name: self.load_table(table_name) for table_name in tables or self.get_tables() }
[docs] def get_dtypes(self, table_name, ids=False, errors=None): """Get a ``dict`` with the ``dtypes`` for each field of a given table. Args: table_name (str): Table name for which to retrive the ``dtypes``. ids (bool): Whether or not include the id fields. Defaults to ``False``. Returns: dict: Dictionary that contains the field names and data types from a table. Raises: ValueError: If a field has an invalid type or subtype or if the table does not exist in this metadata. """ errors = [] if errors is None else errors dtypes = dict() table_meta = self.get_table_meta(table_name) for name, field in table_meta['fields'].items(): field_type = field['type'] field_subtype = field.get('subtype') dtype = self._DTYPES.get((field_type, field_subtype)) if not dtype: errors.append( 'Invalid type and subtype combination for field {}: ({}, {})'.format( name, field_type, field_subtype) ) else: if ids and field_type == 'id': if (name != table_meta.get('primary_key')) and not field.get('ref'): for child_table in self.get_children(table_name): if name in self.get_foreign_keys(table_name, child_table): break if ids or (field_type != 'id'): dtypes[name] = dtype return dtypes
# ################### # # Metadata Validation # # ################### # def _validate_table(self, table_name, table_meta, table_data=None, errors=None): """Validate table metadata. Validate the type and subtype combination for each field in ``table_meta``. If a field has type ``id``, validate that it either is the ``primary_key`` or has a ``ref`` entry. If the table has ``primary_key``, make sure that the corresponding field exists and its type is ``id``. If ``table_data`` is provided, also check that the list of columns corresponds to the ones indicated in the metadata and that all the dtypes are valid. Args: table_name (str): Name of the table to validate. table_meta (dict): Metadata of the table to validate. table_data (pandas.DataFrame): If provided, make sure that the data matches the one described on the metadata. Raises: MetadataError: If there is any error in the metadata or the data does not match the metadata description. """ errors = [] if errors is None else errors dtypes = self.get_dtypes(table_name, ids=True, errors=errors) # Primary key field exists and its type is 'id' primary_key = table_meta.get('primary_key') if primary_key: pk_field = table_meta['fields'].get(primary_key) if not pk_field: errors.append( f'Invalid primary key: "{primary_key}" not found in table "{table_name}"') elif pk_field['type'] != 'id': errors.append( f'Primary key "{primary_key}" of table "{table_name}" not of type "id"') if table_data is not None: for column in table_data: try: dtype = dtypes.pop(column) table_data[column].dropna().astype(dtype) except KeyError: message = 'Unexpected column in table `{}`: `{}`'.format(table_name, column) errors.append(message) except ValueError as ve: message = 'Invalid values found in column `{}` of table `{}`: `{}`'.format( column, table_name, ve) errors.append(message) # assert all dtypes are in data if dtypes: errors.append( 'Missing columns on table {}: {}.'.format(table_name, list(dtypes.keys())) ) def _validate_circular_relationships(self, parent, children=None, errors=None, parents=None): """Validate that there is no circular relatioship in the metadata.""" errors = [] if errors is None else errors parents = set() if parents is None else parents if children is None: children = self.get_children(parent) if parent in children: error = 'Circular relationship found for table "{}"'.format(parent) errors.append(error) for child in children: if child in parents: break parents.add(child) self._validate_circular_relationships( parent, self.get_children(child), errors, parents)
[docs] def validate(self, tables=None): """Validate this metadata. Validate the metadata of each table: * If ``tables`` are provided or they have been loaded, check that all the metadata tables exists in the ``tables`` dictionary. * Validate the type/subtype combination for each field and if a field of type ``id`` exists it must be the ``primary_key`` or must have a ``ref`` entry. * If ``primary_key`` entry exists, check that it's an existing field and its type is ``id``. * If ``tables`` are provided or they have been loaded, check all the data types for the table correspond to each column and all the data types exists on the table. * Validate that there is no circular relatioship in the metadata. * Check that all the tables have at most one parent. Args: tables (bool, dict): If a dict of table is passed, validate that the columns and dtypes match the metadata. If ``True`` is passed, load the tables from the Metadata instead. If ``None``, omit the data validation. Defaults to ``None``. """ tables_meta = self._metadata.get('tables') if not tables_meta: raise MetadataError('"tables" entry not found in Metadata.') if tables and not isinstance(tables, dict): tables = self.load_tables() errors = [] for table_name, table_meta in tables_meta.items(): if tables: table = tables.get(table_name) if table is None: errors.append('Table `{}` not found in tables'.format(table_name)) else: table = None self._validate_table(table_name, table_meta, table, errors) self._validate_circular_relationships(table_name, errors=errors) if errors: raise MetadataError('Invalid Metadata specification:\n - ' + '\n - '.join(errors))
def _check_field(self, table, field, exists=False): """Validate the existance of the table and existance (or not) of field.""" table_fields = self.get_fields(table) if exists and (field not in table_fields): raise ValueError('Field "{}" does not exist in table "{}"'.format(field, table)) if not exists and (field in table_fields): raise ValueError('Field "{}" already exists in table "{}"'.format(field, table)) # ################# # # Metadata Creation # # ################# #
[docs] def add_field(self, table, field, field_type, field_subtype=None, properties=None): """Add a new field to the indicated table. Args: table (str): Table name to add the new field, it must exist. field (str): Field name to be added, it must not exist. field_type (str): Data type of field to be added. Required. field_subtype (str): Data subtype of field to be added. Optional. Defaults to ``None``. properties (dict): Extra properties of field like: ref, format, min, max, etc. Optional. Defaults to ``None``. Raises: ValueError: If the table does not exist or it already contains the field. """ self._check_field(table, field, exists=False) field_details = { 'type': field_type } if field_subtype: field_details['subtype'] = field_subtype if properties: field_details.update(properties) self._metadata['tables'][table]['fields'][field] = field_details
@staticmethod def _get_key_subtype(field_meta): """Get the appropriate key subtype.""" field_type = field_meta['type'] if field_type == 'categorical': field_subtype = 'string' elif field_type in ('numerical', 'id'): field_subtype = field_meta['subtype'] if field_subtype not in ('integer', 'string'): raise ValueError( 'Invalid field "subtype" for key field: "{}"'.format(field_subtype) ) else: raise ValueError( 'Invalid field "type" for key field: "{}"'.format(field_type) ) return field_subtype
[docs] def set_primary_key(self, table, field): """Set the primary key field of the indicated table. The field must exist and either be an integer or categorical field. Args: table (str): Name of the table where the primary key will be set. field (str): Name of the field to be used as the new primary key. Raises: ValueError: If the table or the field do not exist or if the field has an invalid type or subtype. """ self._check_field(table, field, exists=True) field_meta = self.get_fields(table).get(field) field_subtype = self._get_key_subtype(field_meta) table_meta = self._metadata['tables'][table] table_meta['fields'][field] = { 'type': 'id', 'subtype': field_subtype } table_meta['primary_key'] = field
[docs] def add_relationship(self, parent, child, foreign_key=None, validate=True): """Add a new relationship between the parent and child tables. The relationship is created by adding a reference (``ref``) on the ``foreign_key`` field of the ``child`` table pointing at the ``parent`` primary key. Args: parent (str): Name of the parent table. child (str): Name of the child table. foreign_key (str): Field in the child table through which the relationship is created. If ``None``, use the parent primary key name. validate (bool): Whether to validate metadata after adding this relationship or not. Defaults to ``True``. Raises: ValueError: If any of the following happens: * The parent table does not exist. * The child table does not exist. * The parent table does not have a primary key. * The foreign_key field already exists in the child table. * The child table already has a parent. * The new relationship closes a relationship circle. """ # Make a backup metadata_backup = copy.deepcopy(self._metadata) # Validate tables exists self.get_table_meta(parent) self.get_table_meta(child) # Validate field names primary_key = self.get_primary_key(parent) if not primary_key: raise ValueError('Parent table "{}" does not have a primary key'.format(parent)) if foreign_key is None: foreign_key = primary_key parent_key_meta = copy.deepcopy(self.get_field_meta(parent, primary_key)) child_key_meta = copy.deepcopy(self.get_field_meta(child, foreign_key)) # Validate relationships child_ref = child_key_meta.get('ref') if child_ref: raise ValueError( 'Field "{}.{}" already defines a relationship'.format(child, foreign_key)) # Make sure that the parent key is an id if parent_key_meta['type'] != 'id': parent_key_meta['subtype'] = self._get_key_subtype(parent_key_meta) parent_key_meta['type'] = 'id' # Update the child key meta child_key_meta['subtype'] = self._get_key_subtype(child_key_meta) child_key_meta['type'] = 'id' child_key_meta['ref'] = { 'table': parent, 'field': primary_key } # Make sure that key subtypes are the same if child_key_meta['subtype'] != parent_key_meta['subtype']: raise ValueError('Parent and Child key subtypes mismatch') self._metadata['tables'][parent]['fields'][primary_key] = parent_key_meta self._metadata['tables'][child]['fields'][foreign_key] = child_key_meta # Re-analyze the relationships self._analyze_relationships() if validate: try: self.validate() except MetadataError: self._metadata = metadata_backup raise
def _get_field_details(self, data, fields): """Get or build all the fields metadata. Analyze a ``pandas.DataFrame`` to build a ``dict`` with the name of the column, and their data type and subtype. If ``columns`` are provided, only those columns will be analyzed. Args: data (pandas.DataFrame): Table to be analyzed. fields (set): Set of field names or field specifications. Returns: dict: Dict of valid fields. Raises: TypeError: If a field specification is not a str or a dict. ValueError: If a column from the data analyzed is an unsupported data type or """ fields_metadata = dict() for field in fields: dtype = data[field].dtype field_template = self._FIELD_TEMPLATES.get(dtype.kind) if not field_template: raise ValueError('Unsupported dtype {} in column {}'.format(dtype, field)) field_details = copy.deepcopy(field_template) fields_metadata[field] = field_details return fields_metadata
[docs] def add_table(self, name, data=None, fields=None, fields_metadata=None, primary_key=None, parent=None, foreign_key=None, constraints=None): """Add a new table to this metadata. ``fields`` list can be a mixture of field names, which will be build automatically from the data, or dictionaries specifying the field details. If a field needs to be analyzed, data has to be also passed. If ``parent`` is given, a relationship will be established between this table and the specified parent. Args: name (str): Name of the new table. data (str or pandas.DataFrame): Table to be analyzed or path to the csv file. If it's a relative path, use ``root_path`` to find the file. Only used if fields is not ``None``. Defaults to ``None``. fields (list): List of field names to build. If ``None`` is given, all the fields found in the data will be used. Defaults to ``None``. fields_metadata (dict): Metadata to be used when creating fields. This will overwrite the metadata built from the fields found in data. Defaults to ``None``. primary_key (str): Field name to add as primary key, it must not exists. Defaults to ``None``. parent (str): Table name to refere a foreign key field. Defaults to ``None``. foreign_key (str): Foreign key field name to ``parent`` table primary key. Defaults to ``None``. constraints (list[Constraint, dict]): List of Constraint objects or dicts representing the constraints for the given table. Raises: ValueError: If the table ``name`` already exists or ``data`` is not passed and fields need to be built from it. """ if name in self.get_tables(): raise ValueError('Table "{}" already exists.'.format(name)) path = None if data is not None: if isinstance(data, str): path = data if not os.path.isabs(data): data = os.path.join(self.root_path, data) data = pd.read_csv(data) fields = fields or data.columns if fields_metadata: fields = [field for field in fields if field not in fields_metadata] else: fields_metadata = dict() fields_metadata.update(self._get_field_details(data, fields)) elif fields_metadata is None: fields_metadata = dict() table_metadata = {'fields': fields_metadata} if path: table_metadata['path'] = path self._metadata['tables'][name] = table_metadata if constraints: meta_constraints = [] for constraint in constraints: if isinstance(constraint, Constraint): meta_constraints.append(constraint.to_dict()) else: meta_constraints.append(constraint) table_metadata['constraints'] = meta_constraints try: if primary_key: self.set_primary_key(name, primary_key) if parent: self.add_relationship(parent, name, foreign_key) except ValueError: # Cleanup del self._metadata['tables'][name] raise
# ###################### # # Metadata Serialization # # ###################### #
[docs] def to_dict(self): """Get a dict representation of this metadata. Returns: dict: dict representation of this metadata. """ return copy.deepcopy(self._metadata)
[docs] def to_json(self, path): """Dump this metadata into a JSON file. Args: path (str): Path of the JSON file where this metadata will be stored. """ with open(path, 'w') as out_file: json.dump(self._metadata, out_file, indent=4)
def __repr__(self): tables = self.get_tables() relationships = [ ' {}.{} -> {}.{}'.format( table, foreign_key, parent, self.get_primary_key(parent) ) for table in tables for parent in list(self.get_parents(table)) for foreign_key in self.get_foreign_keys(parent, table) ] return ( "Metadata\n" " root_path: {}\n" " tables: {}\n" " relationships:\n" "{}" ).format( self.root_path, tables, '\n'.join(relationships) )
[docs] def visualize(self, path=None, names=True, details=True): """Plot metadata usign graphviz. Generate a plot using graphviz. If a ``path`` is provided save the output into a file. Args: path (str): Output file path to save the plot. It requires a graphviz supported extension. If ``None`` do not save the plot and just return the ``graphviz.Digraph`` object. Defaults to ``None``. names (bool): Whether to add names to the diagram or not. Defaults to ``True`` """ return visualization.visualize(self, path, names=names, details=details)