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""" |
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ETLT |
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Copyright 2016 Set Based IT Consultancy |
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Licence MIT |
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""" |
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import copy |
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import datetime |
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class Type2Helper: |
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""" |
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A helper class for reference data with date intervals. |
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""" |
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# ------------------------------------------------------------------------------------------------------------------ |
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def __init__(self, key_start_date, key_end_date, natural_key): |
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""" |
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Object constructor. |
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:param str key_start_date: The key of the start date in the rows. |
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:param str key_end_date: The key of the end date in the rows. |
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:param list[str] natural_key: The keys of the columns that form the natural key. |
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""" |
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self._natural_key = list(natural_key) |
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""" |
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The keys of the columns that form the natural key. |
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:type list[str]: |
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""" |
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self._key_end_date = key_end_date |
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""" |
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The key of the end date in the rows. |
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:type str: |
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""" |
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self._key_start_date = key_start_date |
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""" |
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The key of the start date in the rows. |
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:type str: |
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""" |
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self.rows = dict() |
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""" |
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The data set. |
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:type dict: |
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""" |
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self._copy = True |
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""" |
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If set to true a copy will be made from the original rows such that the original rows is not modified. |
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:type bool: |
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""" |
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self._date_type = '' |
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""" |
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The type of the date fields. |
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- date for datetime.date objects |
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- str for strings in ISO 8601 (YYYY-MM-DD) format |
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- int for integers |
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:type str: |
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""" |
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# ------------------------------------------------------------------------------------------------------------------ |
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def _get_natural_key(self, row): |
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""" |
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Returns the natural key in a row. |
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:param dict row: The row. |
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:rtype: tuple |
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""" |
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ret = list() |
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for key in self._natural_key: |
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ret.append(row[key]) |
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return tuple(ret) |
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# ------------------------------------------------------------------------------------------------------------------ |
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@staticmethod |
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def _date2int(date): |
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""" |
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Returns an integer representation of a date. |
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:param str|datetime.date date: The date. |
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:rtype: int |
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""" |
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if isinstance(date, str): |
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tmp = datetime.datetime.strptime(date, '%Y-%m-%d') |
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return tmp.toordinal() |
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if isinstance(date, datetime.date): |
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return date.toordinal() |
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if isinstance(date, int): |
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return date |
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raise ValueError('Unexpected type {0!s}'.format(date.__class__)) |
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# ------------------------------------------------------------------------------------------------------------------ |
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def _rows_date2int(self, rows): |
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""" |
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Replaces start and end dates in a row set with their integer representation |
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:param list[dict[str,T]] rows: The list of rows. |
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:rtype: list[dict[str,T]] |
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""" |
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ret = list() |
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for row in rows: |
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# Determine the type of dates based on the first start date. |
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if not self._date_type: |
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self._date_type = self._get_date_type(row[self._key_start_date]) |
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# Convert dates to integers. |
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row[self._key_start_date] = self._date2int(row[self._key_start_date]) |
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row[self._key_end_date] = self._date2int(row[self._key_end_date]) |
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ret.append(row) |
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return ret |
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# ------------------------------------------------------------------------------------------------------------------ |
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def _rows_int2date(self, rows): |
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""" |
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Replaces start and end dates in the row set with their integer representation |
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:param list[dict[str,T]] rows: The list of rows. |
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""" |
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for row in rows: |
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if self._date_type == 'str': |
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row[self._key_start_date] = datetime.date.fromordinal(row[self._key_start_date]).isoformat() |
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row[self._key_end_date] = datetime.date.fromordinal(row[self._key_end_date]).isoformat() |
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elif self._date_type == 'date': |
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row[self._key_start_date] = datetime.date.fromordinal(row[self._key_start_date]) |
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row[self._key_end_date] = datetime.date.fromordinal(row[self._key_end_date]) |
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elif self._date_type == 'int': |
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# Nothing to do. |
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pass |
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else: |
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raise ValueError('Unexpected date type {0!s}'.format(self._date_type)) |
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# ------------------------------------------------------------------------------------------------------------------ |
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def _rows_sort(self, rows): |
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""" |
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Returns a list of rows sorted by start and end date. |
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:param list[dict[str,T]] rows: The list of rows. |
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:rtype: list[dict[str,T]] |
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""" |
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return sorted(rows, key=lambda row: (row[self._key_start_date], row[self._key_end_date])) |
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# ------------------------------------------------------------------------------------------------------------------ |
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@staticmethod |
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def _get_date_type(date): |
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""" |
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Returns the type of a date. |
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:param str|datetime.date date: The date. |
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:rtype: str |
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""" |
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if isinstance(date, str): |
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return 'str' |
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if isinstance(date, datetime.date): |
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return 'date' |
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if isinstance(date, int): |
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return 'int' |
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raise ValueError('Unexpected type {0!s}'.format(date.__class__)) |
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# ------------------------------------------------------------------------------------------------------------------ |
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def enumerate(self, name, start=1): |
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""" |
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Enumerates all rows such that the natural key and the ordinal number are a unique key. |
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:param str name: The key holding the ordinal number. |
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:param start: The start of the ordinal numbers. Foreach natural key the first row has this ordinal number. |
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""" |
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for natural_key, rows in self.rows.items(): |
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rows = self._rows_sort(rows) |
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ordinal = start |
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for row in rows: |
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row[name] = ordinal |
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ordinal += 1 |
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self.rows[natural_key] = rows |
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# ------------------------------------------------------------------------------------------------------------------ |
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def get_rows(self, sort=False): |
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""" |
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Returns the rows of this Type2Helper. |
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:param bool sort: If True the rows are sorted by the natural key. |
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""" |
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ret = [] |
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for _, rows in sorted(self.rows.items()) if sort else self.rows.items(): |
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self._rows_int2date(rows) |
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ret.extend(rows) |
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return ret |
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# ------------------------------------------------------------------------------------------------------------------ |
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def prepare_data(self, rows): |
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""" |
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Sets and prepares the rows. The rows are stored in groups in a dictionary. A group is a list of rows with the |
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same natural key. The key in the dictionary is a tuple with the values of the natural key. |
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:param list[dict] rows: The rows |
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""" |
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self.rows = dict() |
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for row in copy.copy(rows) if self._copy else rows: |
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natural_key = self._get_natural_key(row) |
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if natural_key not in self.rows: |
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self.rows[natural_key] = list() |
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self.rows[natural_key].append(row) |
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# Convert begin and end dates to integers. |
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self._date_type = None |
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for natural_key, rows in self.rows.items(): |
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self.rows[natural_key] = self._rows_date2int(rows) |
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# ---------------------------------------------------------------------------------------------------------------------- |
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