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# (C) Copyright 2005-2023 Enthought, Inc., Austin, TX
# All rights reserved.
#
# This software is provided without warranty under the terms of the BSD
# license included in LICENSE.txt and may be redistributed only under
# the conditions described in the aforementioned license. The license
# is also available online at http://www.enthought.com/licenses/BSD.txt
#
# Thanks for using Enthought open source!
import csv
from functools import partial
from io import BytesIO, StringIO
import os
import json
from pyface.data_view.i_data_wrapper import DataFormat, text_format
# Scalar formats
def to_json(data, default=None):
""" Serialize an object to a JSON bytestring.
Parameters
----------
data : Any
The data to be serialized.
default : Callable or None
Callable that takes a Python object and returns a JSON-serializable
data structure.
Returns
-------
raw_data : bytes
The serialized data as a bytestring.
"""
str_data = json.dumps(data, default=default, separators=(',', ':'))
return str_data.encode('utf-8')
def from_json(raw_data, object_hook=None):
""" Deserialize a JSON bytestring.
Parameters
----------
raw_data : bytes
The serialized JSON data as a byte string.
object_hook : Callable
Callable that takes a dictionary and returns an corresponding
Python object.
Returns
-------
data : Any
The data extracted.
"""
return json.loads(raw_data.decode('utf-8'), object_hook=object_hook)
#: The text/plain format with utf-8 encoding.
standard_text_format = text_format()
#: The text/html format with utf-8 encoding.
html_format = text_format(mimetype='text/html')
#: A generic JSON format.
json_format = DataFormat('application/json', to_json, from_json)
# 1D formats
def to_csv_row(data, delimiter=',', encoding='utf-8', **kwargs):
""" Serialize a list to a single-row CSV bytestring.
Parameters
----------
data : list
The list to be serialized. Any elements which are not strings will
be converted to strings by calling ``str()``.
delimiter : str
The CSV delimiter.
encoding : str
The encoding of the bytes
**kwargs
Additional arguments to csv.writer.
Returns
-------
raw_data : bytes
The serialized data as a bytestring.
"""
fp = StringIO()
writer = csv.writer(fp, delimiter=delimiter, **kwargs)
writer.writerow(data)
return fp.getvalue().encode(encoding)
def from_csv_row(raw_data, delimiter=',', encoding='utf-8', **kwargs):
""" Deserialize the first row of a CSV bytestring as a list.
Any rows beyond the first are ignored.
Parameters
----------
raw_data : bytes
The serialized CSV data as a byte string.
delimiter : str
The CSV delimiter.
encoding : str
The encoding of the bytes
**kwargs
Additional arguments to csv.reader.
Returns
-------
data : list of str
The data extracted as a list of strings.
"""
fp = StringIO(raw_data.decode(encoding))
reader = csv.reader(fp, delimiter=delimiter, **kwargs)
return next(reader)
def to_csv_column(data, delimiter=',', encoding='utf-8', **kwargs):
""" Serialize a list to a single-column CSV bytestring.
Parameters
----------
data : list
The list to be serialized. Any elements which are not strings will
be converted to strings by calling ``str()``.
delimiter : str
The CSV delimiter.
encoding : str
The encoding of the bytes
**kwargs
Additional arguments to csv.writer.
Returns
-------
raw_data : bytes
The serialized data as a bytestring.
"""
fp = StringIO()
writer = csv.writer(fp, delimiter=delimiter, **kwargs)
for row in data:
writer.writerow([row])
return fp.getvalue().encode(encoding)
def from_csv_column(raw_data, delimiter=',', encoding='utf-8', **kwargs):
""" Deserialize the first column of a CSV bytestring as a list.
Any columns beyond the first are ignored.
Parameters
----------
raw_data : bytes
The serialized CSV data as a byte string.
delimiter : str
The CSV delimiter.
encoding : str
The encoding of the bytes
**kwargs
Additional arguments to csv.reader.
Returns
-------
data : list of str
The data extracted as a list of strings.
"""
fp = StringIO(raw_data.decode(encoding))
reader = csv.reader(fp, delimiter=delimiter, **kwargs)
return [row[0] for row in reader]
text_row_format = DataFormat(
'text/plain',
partial(to_csv_row, delimiter='\t', lineterminator=os.linesep),
partial(from_csv_row, delimiter='\t'),
)
csv_row_format = DataFormat('text/csv', to_csv_row, from_csv_row)
text_column_format = DataFormat(
'text/plain',
partial(to_csv_column, delimiter='\t', lineterminator=os.linesep),
partial(from_csv_column, delimiter='\t'),
)
csv_column_format = DataFormat('text/csv', to_csv_column, from_csv_column)
# 2D formats
def to_csv(data, delimiter=',', encoding='utf-8', **kwargs):
""" Serialize a list of lists to a CSV bytestring.
Parameters
----------
data : list of lists
The data to be serialized. Any elements which are not strings will
be converted to strings by calling ``str()``.
delimiter : str
The CSV delimiter.
encoding : str
The encoding of the bytes
**kwargs
Additional arguments to csv.writer.
Returns
-------
raw_data : bytes
The serialized data as a bytestring.
"""
fp = StringIO()
writer = csv.writer(fp, delimiter=delimiter, **kwargs)
for row in data:
writer.writerow(row)
return fp.getvalue().encode(encoding)
def from_csv(raw_data, delimiter=',', encoding='utf-8', **kwargs):
""" Deserialize a CSV bytestring.
Parameters
----------
raw_data : bytes
The serialized CSV data as a byte string.
delimiter : str
The CSV delimiter.
encoding : str
The encoding of the bytes
**kwargs
Additional arguments to csv.reader.
Returns
-------
data : list of list of str
The data extracted as a list of lists of strings.
"""
fp = StringIO(raw_data.decode(encoding))
reader = csv.reader(fp, delimiter=delimiter, **kwargs)
return list(reader)
def to_npy(data):
""" Serialize an array to a bytestring using .npy format.
Parameters
----------
data : array-like
The array to be serialized.
Returns
-------
raw_data : bytes
The serialized data as a bytestring.
"""
import numpy as np
data = np.atleast_2d(data)
fp = BytesIO()
np.save(fp, data, allow_pickle=False)
return fp.getvalue()
def from_npy(raw_data):
""" Deserialize a .npy-format bytestring.
Parameters
----------
raw_data : bytes
The serialized CSV data as a byte string.
Returns
-------
data : list of list of str
The data extracted as a list of lists of strings.
"""
import numpy as np
fp = BytesIO(raw_data)
return np.load(fp, allow_pickle=False)
table_format = DataFormat(
'text/plain',
partial(to_csv, delimiter='\t', lineterminator=os.linesep),
partial(from_csv, delimiter='\t'),
)
csv_format = DataFormat('text/csv', to_csv, from_csv)
npy_format = DataFormat('application/x-npy', to_npy, from_npy)
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