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from __future__ import absolute_import, print_function, division
import datetime
from petl.compat import long
def datetimeparser(fmt, strict=True):
"""Return a function to parse strings as :class:`datetime.datetime` objects
using a given format. E.g.::
>>> from petl import datetimeparser
>>> isodatetime = datetimeparser('%Y-%m-%dT%H:%M:%S')
>>> isodatetime('2002-12-25T00:00:00')
datetime.datetime(2002, 12, 25, 0, 0)
>>> try:
... isodatetime('2002-12-25T00:00:99')
... except ValueError as e:
... print(e)
...
unconverted data remains: 9
If ``strict=False`` then if an error occurs when parsing, the original
value will be returned as-is, and no error will be raised.
"""
def parser(value):
try:
return datetime.datetime.strptime(value.strip(), fmt)
except Exception as e:
if strict:
raise e
else:
return value
return parser
def dateparser(fmt, strict=True):
"""Return a function to parse strings as :class:`datetime.date` objects
using a given format. E.g.::
>>> from petl import dateparser
>>> isodate = dateparser('%Y-%m-%d')
>>> isodate('2002-12-25')
datetime.date(2002, 12, 25)
>>> try:
... isodate('2002-02-30')
... except ValueError as e:
... print(e)
...
day is out of range for month
If ``strict=False`` then if an error occurs when parsing, the original
value will be returned as-is, and no error will be raised.
"""
def parser(value):
try:
return datetime.datetime.strptime(value.strip(), fmt).date()
except Exception as e:
if strict:
raise e
else:
return value
return parser
def timeparser(fmt, strict=True):
"""Return a function to parse strings as :class:`datetime.time` objects
using a given format. E.g.::
>>> from petl import timeparser
>>> isotime = timeparser('%H:%M:%S')
>>> isotime('00:00:00')
datetime.time(0, 0)
>>> isotime('13:00:00')
datetime.time(13, 0)
>>> try:
... isotime('12:00:99')
... except ValueError as e:
... print(e)
...
unconverted data remains: 9
>>> try:
... isotime('25:00:00')
... except ValueError as e:
... print(e)
...
time data '25:00:00' does not match format '%H:%M:%S'
If ``strict=False`` then if an error occurs when parsing, the original
value will be returned as-is, and no error will be raised.
"""
def parser(value):
try:
return datetime.datetime.strptime(value.strip(), fmt).time()
except Exception as e:
if strict:
raise e
else:
return value
return parser
def boolparser(true_strings=('true', 't', 'yes', 'y', '1'),
false_strings=('false', 'f', 'no', 'n', '0'),
case_sensitive=False,
strict=True):
"""Return a function to parse strings as :class:`bool` objects using a
given set of string representations for `True` and `False`. E.g.::
>>> from petl import boolparser
>>> mybool = boolparser(true_strings=['yes', 'y'], false_strings=['no', 'n'])
>>> mybool('y')
True
>>> mybool('yes')
True
>>> mybool('Y')
True
>>> mybool('No')
False
>>> try:
... mybool('foo')
... except ValueError as e:
... print(e)
...
value is not one of recognised boolean strings: 'foo'
>>> try:
... mybool('True')
... except ValueError as e:
... print(e)
...
value is not one of recognised boolean strings: 'true'
If ``strict=False`` then if an error occurs when parsing, the original
value will be returned as-is, and no error will be raised.
"""
if not case_sensitive:
true_strings = [s.lower() for s in true_strings]
false_strings = [s.lower() for s in false_strings]
def parser(value):
value = value.strip()
if not case_sensitive:
value = value.lower()
if value in true_strings:
return True
elif value in false_strings:
return False
elif strict:
raise ValueError('value is not one of recognised boolean strings: '
'%r' % value)
else:
return value
return parser
def numparser(strict=False):
"""Return a function that will attempt to parse the value as a number,
trying :func:`int`, :func:`long`, :func:`float` and :func:`complex` in
that order. If all fail, return the value as-is, unless ``strict=True``,
in which case raise the underlying exception.
"""
def f(v):
try:
return int(v)
except (ValueError, TypeError):
pass
try:
return long(v)
except (ValueError, TypeError):
pass
try:
return float(v)
except (ValueError, TypeError):
pass
try:
return complex(v)
except (ValueError, TypeError) as e:
if strict:
raise e
return v
return f
|
