Source code for bokeh.util.serialization

# Copyright (c) 2012 - 2022, Anaconda, Inc., and Bokeh Contributors.
# All rights reserved.
# The full license is in the file LICENSE.txt, distributed with this software.
Functions for helping with serialization and deserialization of
Bokeh objects.

Certain NumPy array dtypes can be serialized to a binary format for
performance and efficiency. The list of supported dtypes is:



# Boilerplate
from __future__ import annotations

import logging # isort:skip
log = logging.getLogger(__name__)

# Imports

# Standard library imports
import datetime as dt
import uuid
from functools import lru_cache
from threading import Lock
from typing import TYPE_CHECKING, Any, Type

# External imports
import numpy as np

# Bokeh imports
from ..core.types import ID
from ..settings import settings
from .strings import format_docstring

    import numpy.typing as npt
    import pandas as pd
    from typing_extensions import TypeGuard

# Globals and constants

def _compute_datetime_types() -> set[type]:
    import pandas as pd

    result = {dt.time, dt.datetime, np.datetime64}
    return result

def __getattr__(name: str) -> Any:
    if name == "DATETIME_TYPES":
        return _compute_datetime_types()
    raise AttributeError


NP_EPOCH = np.datetime64(0, 'ms')
NP_MS_DELTA = np.timedelta64(1, 'ms')

DT_EPOCH = dt.datetime.utcfromtimestamp(0)

__doc__ = format_docstring(__doc__, binary_array_types="\n".join(f"* ``np.{x}``" for x in BINARY_ARRAY_TYPES))

__all__ = (

# General API

[docs]def is_datetime_type(obj: Any) -> TypeGuard[dt.time | dt.datetime | np.datetime64]: ''' Whether an object is any date, time, or datetime type recognized by Bokeh. Arg: obj (object) : the object to test Returns: bool : True if ``obj`` is a datetime type ''' _dt_tuple = tuple(_compute_datetime_types()) return isinstance(obj, _dt_tuple)
[docs]def is_timedelta_type(obj: Any) -> TypeGuard[dt.timedelta | np.timedelta64]: ''' Whether an object is any timedelta type recognized by Bokeh. Arg: obj (object) : the object to test Returns: bool : True if ``obj`` is a timedelta type ''' return isinstance(obj, (dt.timedelta, np.timedelta64))
[docs]def convert_date_to_datetime(obj: -> float: ''' Convert a date object to a datetime Args: obj (date) : the object to convert Returns: datetime ''' return (dt.datetime(*obj.timetuple()[:6], tzinfo=None) - DT_EPOCH).total_seconds() * 1000
[docs]def convert_timedelta_type(obj: dt.timedelta | np.timedelta64) -> float: ''' Convert any recognized timedelta value to floating point absolute milliseconds. Arg: obj (object) : the object to convert Returns: float : milliseconds ''' if isinstance(obj, dt.timedelta): return obj.total_seconds() * 1000. elif isinstance(obj, np.timedelta64): return float(obj / NP_MS_DELTA) raise ValueError(f"Unknown timedelta object: {obj!r}")
# The Any here should be pd.NaT | pd.Period but mypy chokes on that for some reason
[docs]def convert_datetime_type(obj: Any | pd.Timestamp | pd.Timedelta | dt.datetime | | dt.time | np.datetime64) -> float: ''' Convert any recognized date, time, or datetime value to floating point milliseconds since epoch. Arg: obj (object) : the object to convert Returns: float : milliseconds ''' import pandas as pd # Pandas NaT if obj is pd.NaT: return np.nan # Pandas Period if isinstance(obj, pd.Period): return obj.to_timestamp().value / 10**6.0 # Pandas Timestamp if isinstance(obj, pd.Timestamp): return obj.value / 10**6.0 # Pandas Timedelta elif isinstance(obj, pd.Timedelta): return obj.value / 10**6.0 # Datetime (datetime is a subclass of date) elif isinstance(obj, dt.datetime): diff = obj.replace(tzinfo=None) - DT_EPOCH return diff.total_seconds() * 1000 # XXX (bev) ideally this would not be here "dates are not datetimes" # Date elif isinstance(obj, return convert_date_to_datetime(obj) # NumPy datetime64 elif isinstance(obj, np.datetime64): epoch_delta = obj - NP_EPOCH return float(epoch_delta / NP_MS_DELTA) # Time elif isinstance(obj, dt.time): return (obj.hour * 3600 + obj.minute * 60 + obj.second) * 1000 + obj.microsecond / 1000. raise ValueError(f"unknown datetime object: {obj!r}")
[docs]def convert_datetime_array(array: npt.NDArray[Any]) -> npt.NDArray[np.floating[Any]]: ''' Convert NumPy datetime arrays to arrays to milliseconds since epoch. Args: array : (obj) A NumPy array of datetime to convert If the value passed in is not a NumPy array, it will be returned as-is. Returns: array ''' # not quite correct, truncates to ms.. if array.dtype.kind == 'M': return array.astype('datetime64[us]').astype('int64') / 1000.0 elif array.dtype.kind == 'm': return array.astype('timedelta64[us]').astype('int64') / 1000.0 # XXX (bev) special case dates, not great elif array.dtype.kind == 'O' and len(array) > 0 and isinstance(array[0], try: return array.astype('datetime64[us]').astype('int64') / 1000.0 except Exception: pass return array
[docs]def make_id() -> ID: ''' Return a new unique ID for a Bokeh object. Normally this function will return simple monotonically increasing integer IDs (as strings) for identifying Bokeh objects within a Document. However, if it is desirable to have globally unique for every object, this behavior can be overridden by setting the environment variable ``BOKEH_SIMPLE_IDS=no``. Returns: str ''' global _simple_id if settings.simple_ids(): with _simple_id_lock: _simple_id += 1 return ID(f"p{_simple_id}") else: return make_globally_unique_id()
[docs]def make_globally_unique_id() -> ID: ''' Return a globally unique UUID. Some situations, e.g. id'ing dynamically created Divs in HTML documents, always require globally unique IDs. Returns: str ''' return ID(str(uuid.uuid4()))
[docs]def array_encoding_disabled(array: npt.NDArray[Any]) -> bool: ''' Determine whether an array may be binary encoded. The NumPy array dtypes that can be encoded are: {binary_array_types} Args: array (np.ndarray) : the array to check Returns: bool ''' # disable binary encoding for non-supported dtypes return array.dtype not in BINARY_ARRAY_TYPES
array_encoding_disabled.__doc__ = format_docstring( array_encoding_disabled.__doc__, binary_array_types="\n ".join(f"* ``np.{x}``" for x in BINARY_ARRAY_TYPES), )
[docs]def transform_array(array: npt.NDArray[Any]) -> npt.NDArray[Any]: ''' Transform a ndarray into a serializable ndarray. Converts un-serializable dtypes and returns JSON serializable format Args: array (np.ndarray) : a NumPy array to be transformed Returns: ndarray ''' array = convert_datetime_array(array) # XXX: as long as we can't support 64-bit integers, try to convert # to 32-bits. If not possible, let the serializer convert to a less # efficient representation and/or deal with any error messaging. def _cast_if_can(array: npt.NDArray[Any], dtype: Type[Any]) -> npt.NDArray[Any]: info = np.iinfo(dtype) if np.any((array < info.min) | (info.max < array)): return array else: return array.astype(dtype, casting="unsafe") if array.dtype == np.dtype(np.int64): array = _cast_if_can(array, np.int32) elif array.dtype == np.dtype(np.uint64): array = _cast_if_can(array, np.uint32) if isinstance(array, array = array.filled(np.nan) # type: ignore # filled is untyped if not array.flags["C_CONTIGUOUS"]: array = np.ascontiguousarray(array) return array
[docs]def transform_series(series: pd.Series[Any] | pd.Index) -> npt.NDArray[Any]: ''' Transforms a Pandas series into serialized form Args: series (pd.Series) : the Pandas series to transform Returns: ndarray ''' import pandas as pd # not checking for pd here, this function should only be called if it # is already known that series is a Pandas Series type if isinstance(series, pd.PeriodIndex): vals = series.to_timestamp().values # type: ignore else: vals = series.values return vals
#----------------------------------------------------------------------------- # Dev API #----------------------------------------------------------------------------- #----------------------------------------------------------------------------- # Private API #----------------------------------------------------------------------------- _simple_id = 999 _simple_id_lock = Lock() #----------------------------------------------------------------------------- # Code #-----------------------------------------------------------------------------