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Datetime Compute#

group datetime_compute

Enums

enum class rounding_frequency : int32_t#

Fixed frequencies supported by datetime rounding functions ceil, floor, round.

Values:

enumerator DAY#
enumerator HOUR#
enumerator MINUTE#
enumerator SECOND#
enumerator MILLISECOND#
enumerator MICROSECOND#
enumerator NANOSECOND#

Functions

std::unique_ptr<cudf::column> last_day_of_month(cudf::column_view const &column, rmm::mr::device_memory_resource *mr = rmm::mr::get_current_device_resource())#

Computes the last day of the month in datetime type and returns a TIMESTAMP_DAYS cudf::column.

Parameters:

  • column – cudf::column_view of the input datetime values

  • mr – Device memory resource used to allocate device memory of the returned column

Throws:

cudf::logic_error – if input column datatype is not TIMESTAMP

Returns:

cudf::column containing last day of the month as TIMESTAMP_DAYS

std::unique_ptr<cudf::column> day_of_year(cudf::column_view const &column, rmm::mr::device_memory_resource *mr = rmm::mr::get_current_device_resource())#

Computes the day number since the start of the year from the datetime and returns an int16_t cudf::column. The value is between [1, {365-366}].

Parameters:

  • column – cudf::column_view of the input datetime values

  • mr – Device memory resource used to allocate device memory of the returned column

Throws:

cudf::logic_error – if input column datatype is not a TIMESTAMP

Returns:

cudf::column of datatype INT16 containing the day number since the start of the year

std::unique_ptr<cudf::column> add_calendrical_months(cudf::column_view const &timestamps, cudf::column_view const &months, rmm::mr::device_memory_resource *mr = rmm::mr::get_current_device_resource())#

Adds or subtracts a number of months from the datetime type and returns a timestamp column that is of the same type as the input timestamps column.

For a given row, if the timestamps or the months column value is null, the output for that row is null. This method preserves the input time and the day where applicable. The date is rounded down to the last day of the month for that year, if the new day is invalid for that month.

Example:
timestamps = [5/31/20 08:00:00, 5/31/20 00:00:00, 5/31/20 13:00:00, 5/31/20 23:00:00,
              6/30/20 00:00:01, 6/30/20 14:12:13]
months     = [1               , -1              , -3              , -15             ,
              -1              , 1]
r = add_calendrical_months(timestamp_column, months_column)
r is [6/30/20 08:00:00, 4/30/20 00:00:00, 2/29/20 13:00:00, 2/28/19 23:00:00,
      5/30/20 00:00:01, 7/30/20 14:12:13]
Throws:

  • cudf::logic_error – if timestamps datatype is not a TIMESTAMP or if months datatype is not INT16 or INT32.

  • cudf::logic_error – if timestamps column size is not equal to months column size.

Parameters:

  • timestamps – cudf::column_view of timestamp type

  • months – cudf::column_view of integer type containing the number of months to add

  • mr – Device memory resource used to allocate device memory of the returned column

Returns:

cudf::column of timestamp type containing the computed timestamps

std::unique_ptr<cudf::column> add_calendrical_months(cudf::column_view const &timestamps, cudf::scalar const &months, rmm::mr::device_memory_resource *mr = rmm::mr::get_current_device_resource())#

Adds or subtracts a number of months from the datetime type and returns a timestamp column that is of the same type as the input timestamps column.

For a given row, if the timestamps value is null, the output for that row is null. A null months scalar would result in an all null column. This method preserves the input time and the day where applicable. The date is rounded down to the last day of the month for that year, if the new day is invalid for that month.

Example:
timestamps = [5/31/20 08:00:00, 6/30/20 00:00:00, 7/31/20 13:00:00]
months     = -3
output is [2/29/20 08:00:00, 3/30/20 00:00:00, 4/30/20 13:00:00]

timestamps = [4/28/20 04:00:00, 5/30/20 01:00:00, 6/30/20 21:00:00]
months     = 1
output is [5/28/20 04:00:00, 6/30/20 01:00:00, 7/30/20 21:00:00]
Throws:

  • cudf::logic_error – if timestamps datatype is not a TIMESTAMP or if months datatype is not INT16 or INT32.

  • cudf::logic_error – if timestamps column size is not equal to months column size.

Parameters:

  • timestamps – cudf::column_view of timestamp type

  • months – cudf::scalar of integer type containing the number of months to add

  • mr – Device memory resource used to allocate device memory of the returned column

Returns:

cudf::column of timestamp type containing the computed timestamps

std::unique_ptr<cudf::column> is_leap_year(cudf::column_view const &column, rmm::mr::device_memory_resource *mr = rmm::mr::get_current_device_resource())#

Check if the year of the given date is a leap year.

output[i] == true if year of column[i] is a leap year output[i] == false if year of column[i] is not a leap year output[i] is null if column[i] is null

Parameters:

  • column – cudf::column_view of the input datetime values

  • mr – Device memory resource used to allocate device memory of the returned column

Throws:

cudf::logic_error – if input column datatype is not a TIMESTAMP

Returns:

cudf::column of datatype BOOL8 truth value of the corresponding date

std::unique_ptr<cudf::column> days_in_month(cudf::column_view const &column, rmm::mr::device_memory_resource *mr = rmm::mr::get_current_device_resource())#

Extract the number of days in the month.

output[i] contains the number of days in the month of date column[i] output[i] is null if column[i] is null

Throws:

cudf::logic_error – if input column datatype is not a TIMESTAMP

Parameters:

  • column – cudf::column_view of the input datetime values

  • mr – Device memory resource used to allocate device memory of the returned column

Returns:

cudf::column of datatype INT16 of days in month of the corresponding date

std::unique_ptr<cudf::column> extract_quarter(cudf::column_view const &column, rmm::mr::device_memory_resource *mr = rmm::mr::get_current_device_resource())#

Returns the quarter of the date.

output[i] will be a value from {1, 2, 3, 4} corresponding to the quarter of month given by column[i]. It will be null if the input row at column[i] is null.

Throws:

cudf::logic_error – if input column datatype is not a TIMESTAMP

Parameters:

  • column – The input column containing datetime values

  • mr – Device memory resource used to allocate device memory of the returned column

Returns:

A column of INT16 type indicating which quarter the date is in

std::unique_ptr<cudf::column> ceil_datetimes(cudf::column_view const &column, rounding_frequency freq, rmm::mr::device_memory_resource *mr = rmm::mr::get_current_device_resource())#

Round datetimes up to the nearest multiple of the given frequency.

Parameters:

  • column – cudf::column_view of the input datetime values

  • freq – rounding_frequency indicating the frequency to round up to

  • mr – Device memory resource used to allocate device memory of the returned column

Throws:

cudf::logic_error – if input column datatype is not TIMESTAMP.

Returns:

cudf::column of the same datetime resolution as the input column

std::unique_ptr<cudf::column> floor_datetimes(cudf::column_view const &column, rounding_frequency freq, rmm::mr::device_memory_resource *mr = rmm::mr::get_current_device_resource())#

Round datetimes down to the nearest multiple of the given frequency.

Parameters:

  • column – cudf::column_view of the input datetime values

  • freq – rounding_frequency indicating the frequency to round down to

  • mr – Device memory resource used to allocate device memory of the returned column

Throws:

cudf::logic_error – if input column datatype is not TIMESTAMP.

Returns:

cudf::column of the same datetime resolution as the input column

std::unique_ptr<cudf::column> round_datetimes(cudf::column_view const &column, rounding_frequency freq, rmm::mr::device_memory_resource *mr = rmm::mr::get_current_device_resource())#

Round datetimes to the nearest multiple of the given frequency.

Parameters:

  • column – cudf::column_view of the input datetime values

  • freq – rounding_frequency indicating the frequency to round to

  • mr – Device memory resource used to allocate device memory of the returned column

Throws:

cudf::logic_error – if input column datatype is not TIMESTAMP.

Returns:

cudf::column of the same datetime resolution as the input column

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