flowmachine.core.hour_slice

Class DayOfWeekPeriod

DayOfWeekPeriod(weekday: str)

Source: flowmachine/core/hour_slice.py

Represents a repeated "day-of-the-week" time period.

Parameters

• weekday: str

  The weekday during which this day period is repeated every week. Should be one of: 'Monday', "Tuesday", "Wednesday", etc. (or an equivalent name if a non-English locale is being used).

Methods

filter_timestamp_column_by_day_of_week

filter_timestamp_column_by_day_of_week(self, ts_col: sqlalchemy.orm.attributes.InstrumentedAttribute)

Source: flowmachine/core/hour_slice.py

Returns a sql expression which filters the timestamp column

Class DayPeriod

DayPeriod(weekday=None)

Source: flowmachine/core/hour_slice.py

Represents a repeated "daily" time period.

Parameters

• weekday: None

  This argument must be None for DayPeriod (it only exists for compatibility with the sister class DayOfWeekPeriod). An error is raised if a different value is passed.

Methods

filter_timestamp_column_by_day_of_week

filter_timestamp_column_by_day_of_week(self, ts_col: sqlalchemy.orm.attributes.InstrumentedAttribute) -> sqlalchemy.sql.elements.ColumnElement

Source: flowmachine/core/hour_slice.py

Returns an expression equivalent to TRUE (because no additional filtering is needed to limit the day of the week).

Parameters

• ts_col: sqlalchemy.orm.attributes.InstrumentedAttribute

  The timestamp column to filter. Note that this input argument is ignored for the DayPeriod class because it requires no additional filtering to limit the day of the week.

Returns

• sqlalchemy.sql.elements.ColumnElement

Class HourAndMinutesTimestamp

HourAndMinutesTimestamp(hour_str, **kwargs)

Source: flowmachine/core/hour_slice.py

Represents an HH:MM period of the day and allows filtering a timestamp column accordingly.

Parameters

• hour_str: str

  A string in the format 'HH:MM'.

Methods

filter_timestamp_column

filter_timestamp_column(self, ts_col, cmp_op: <built-in function callable>) -> sqlalchemy.sql.elements.ColumnElement

Source: flowmachine/core/hour_slice.py

Filter timestamp column by comparing to this hour-of-day using the given comparison operator.

Parameters

• ts_col: sqlalchemy column

  The timestamp column to filter.

• cmp_op: callable

  Comparison operator to use. For example: operator.lt, operator.ge.

Returns

• sqlalchemy.sql.elements.ColumnElement

  Sqlalchemy expression representing the filtered timestamp column. This can be used in WHERE clauses of other sql queries.

Class HourInterval

HourInterval(*, start_hour: str, stop_hour: str, freq: str, weekday: str = None)

Source: flowmachine/core/hour_slice.py

Represents an interval of hours during the day which is repeated regularly, for example each day, or every Tuesday. The interval is considered to be half-open, i.e. the left endpoint is included and the right endpoint is excluded. For example: 08:30 <= HH:MM < 16:00.

Parameters

• start_hour: str

  Start hour of this hour interval in the format 'HH:MM' (e.g. '08:00'). The start hour can also be None, indicating that the hour interval starts at midnight at the beginning of the day.

• stop_hour: str

  Stop hour of this hour interval in the format 'HH:MM' (e.g. '19:30'). The stop hour can also be None, indicating that the hour interval extends until midnight.

• freq: str

  Frequency at which the underlying time interval is repeated. This must be either "day" or "week". In the latter case the weekday argument must also be provided.

• weekday: str, default None

  The day of the week for which this hour interval is valid. This argument is only relevant if freq="week" and is ignored otherwise.

Methods

filter_timestamp_column

filter_timestamp_column(self, ts_col) -> sqlalchemy.sql.elements.ColumnElement

Source: flowmachine/core/hour_slice.py

Filter timestamp column using this hour interval.

Parameters

• ts_col: sqlalchemy column

  The timestamp column to filter.

Returns

• sqlalchemy.sql.elements.ColumnElement

  Sqlalchemy expression representing the filtered timestamp column. This can be used in WHERE clauses of other sql queries.

Class HourSlice

HourSlice(*, hour_intervals: List[flowmachine.core.hour_slice.HourInterval])

Source: flowmachine/core/hour_slice.py

Represents a collection of multiple non-overlapping hour intervals.

Parameters

• hour_intervals: typing.List

  List of hour interval. These are assumed to be non-overlapping (but note that this is not currently enforced).

Methods

get_subsetting_condition

get_subsetting_condition(self, ts_col) -> sqlalchemy.sql.elements.ColumnElement

Source: flowmachine/core/hour_slice.py

Return sqlalchemy expression which represents subsetting the given timestamp column by hours of the day.

Parameters

• ts_col: sqlalchemy column

  The timestamp column to which to apply the subsetting.

Returns

• sqlalchemy.sql.elements.ColumnElement

Class MissingHourAndMinutesTimestamp

MissingHourAndMinutesTimestamp()

Source: flowmachine/core/hour_slice.py

Represents a "missing" HH:MM timestamp. This is used to represent time intervals during the day where the start or end is missing (i.e. extends until midnight)

Methods

filter_timestamp_column

filter_timestamp_column(self, ts_col, cmp_op: <built-in function callable>) -> sqlalchemy.sql.elements.ColumnElement

Source: flowmachine/core/hour_slice.py

Filter timestamp column by comparing to this hour-of-day using the given comparison operator. Note that for the class MissingHourAndMinutesTimestamp this always returns TRUE, since a missing timestamp imposes no constraint.

Parameters

• ts_col: sqlalchemy column

  The timestamp column to filter.

• cmp_op: callable

  Comparison operator to use. For example: operator.lt, operator.ge.

Returns

• sqlalchemy.sql.elements.ColumnElement

make_hour_interval_period

make_hour_interval_period(freq, *, weekday: Optional[str] = None)

Source: flowmachine/core/hour_slice.py

Returns an appropriate instance of DayPeriod or DayOfWeekPeriod, depending on the value of freq.

Parameters

• freq: {"day", "week"}

  Indicated whether the interval period should be repeated every day or on a particular day of the week ("week").

• weekday: typing.Optional, default None

  The weekday during which this day period is repeated every week. If freq="day" then the value of weekday must be None. Otherwise it should be one of: 'Monday', "Tuesday", "Wednesday", etc.

Returns

• DayOfWeekPeriod, DayPeriod