/
feather_format.py
112 lines (82 loc) · 3.29 KB
/
feather_format.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
""" feather-format compat """
from distutils.version import LooseVersion
from pandas import DataFrame, RangeIndex, Int64Index
from pandas.compat import range
from pandas.io.common import _stringify_path
def _try_import():
# since pandas is a dependency of feather
# we need to import on first use
try:
import feather
except ImportError:
# give a nice error message
raise ImportError("the feather-format library is not installed\n"
"you can install via conda\n"
"conda install feather-format -c conda-forge\n"
"or via pip\n"
"pip install -U feather-format\n")
try:
LooseVersion(feather.__version__) >= LooseVersion('0.3.1')
except AttributeError:
raise ImportError("the feather-format library must be >= "
"version 0.3.1\n"
"you can install via conda\n"
"conda install feather-format -c conda-forge"
"or via pip\n"
"pip install -U feather-format\n")
return feather
def to_feather(df, path):
"""
Write a DataFrame to the feather-format
Parameters
----------
df : DataFrame
path : string file path, or file-like object
"""
path = _stringify_path(path)
if not isinstance(df, DataFrame):
raise ValueError("feather only support IO with DataFrames")
feather = _try_import()
valid_types = {'string', 'unicode'}
# validate index
# --------------
# validate that we have only a default index
# raise on anything else as we don't serialize the index
if not isinstance(df.index, Int64Index):
raise ValueError("feather does not support serializing {} "
"for the index; you can .reset_index()"
"to make the index into column(s)".format(
type(df.index)))
if not df.index.equals(RangeIndex.from_range(range(len(df)))):
raise ValueError("feather does not support serializing a "
"non-default index for the index; you "
"can .reset_index() to make the index "
"into column(s)")
if df.index.name is not None:
raise ValueError("feather does not serialize index meta-data on a "
"default index")
# validate columns
# ----------------
# must have value column names (strings only)
if df.columns.inferred_type not in valid_types:
raise ValueError("feather must have string column names")
feather.write_dataframe(df, path)
def read_feather(path, nthreads=1):
"""
Load a feather-format object from the file path
.. versionadded 0.20.0
Parameters
----------
path : string file path, or file-like object
nthreads : int, default 1
Number of CPU threads to use when reading to pandas.DataFrame
.. versionadded 0.21.0
Returns
-------
type of object stored in file
"""
feather = _try_import()
path = _stringify_path(path)
if LooseVersion(feather.__version__) < LooseVersion('0.4.0'):
return feather.read_dataframe(path)
return feather.read_dataframe(path, nthreads=nthreads)