"""Viewers of numpy ndarray

"""

from .utils import get_bitmap

def random(size, nulls=False):

"""Return random numpy.ndarray instance of 64 bit floats.

"""

import numpy as np

r = np.random.random(size)

if nulls:

idx = np.random.randint(0, r.size, size=max(1, r.size//4))

r[idx] = np.nan

return r

def pyarrow_array(arr, nan_to_null=False):

"""Return pyarrow.Array view of a numpy ndarray.

In floating arrays, all nan values are interpreted as nulls.

In complex arrays, if real or imaginary part of an array item

value is nan, the value is interpreted as null.

"""

import numpy as np

import pyarrow as pa

if nan_to_null and issubclass(arr.dtype.type,

(np.floating, np.complexfloating)):

isnan = np.isnan(arr)

if isnan.any():

pa_nul = pa.py_buffer(get_bitmap(isnan))

return pa.Array.from_buffers(pa.from_numpy_dtype(arr.dtype),

arr.size,

[pa_nul, pa.py_buffer(arr)])

return pa.Array.from_buffers(pa.from_numpy_dtype(arr.dtype),

arr.size,

[None, pa.py_buffer(arr)])

def pandas_series(arr, nan_to_null=False):

"""Return pandas.Series view of a numpy ndarray.

"""

import pandas as pd

return pd.Series(arr, copy=False)

def xnd_xnd(arr, nan_to_null=False):

"""Return xnd.xnd view of a numpy ndarray.

"""

import numpy as np

import xnd

xd = xnd.xnd.from_buffer(arr)

if nan_to_null and issubclass(arr.dtype.type,

(np.floating, np.complexfloating)):

isnan = np.isnan(arr)

if isnan.any():

raise NotImplementedError('xnd view of numpy ndarray with nans')

return xd