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A utility designed to process/parse/clean scalars, especially text. (note: in active development)

Project description

License

pydatacleaner

pydatacleaner is a Python library to standardize data and to flexibly render them into the most correct datatypes. It was originally a significant part of the matrixb project to handle errors and inconsistencies when reading in data files.

The core DataCleaner class is a general base class and has functions primarily designed to look at text values and convert them to numbers, dates, booleans, etc, as appropriate. The convert_{datatype} properties indicate which types should be investigated, which triggers the parse_{datatype} as eligible.

Subclasses of datacleaner include SnakeCase and CamelCase, and as suggested, will convert strings to their snake or camel versions, and can translate between each other via the tokenize() and join() functions, which are abstract in the DataCleaner baseclass.

Distribution

Project Status

Currently, pydatacleaner is functional but shallowly vetted condition and should be considered beta software. Your mileage may vary. In particular, some of the non-default features, such as required typecasting, are slated to be refactored and haven't been examined thoroughly in a while.

Code comments of NOTE and TODO indicate known shortcomings that may be useful to you. The interface will likely change in future versions.

If you wish to rely on features of this package, I am likely more than willing to accommodate and to incorporate sensible design improvements or, in some cases, changes.

Limitations and Future Directions

The clean function is relatively slow, especially when considering all data translations for large datasets of many millions of cells. I plan to build in eventual performance improvements by writing many of the core data processing in C instead of using the pure-python version, but I don't have a specific timeline for this.

Installation

Use the package manager pip to install pydatacleaner.

pip install pydatacleaner

Usage

Many examples of usage are available in the main test files included in the t/ subdirectory.

import datacleaner

#
# Auto-translating various null values to None
#

default_null_values = ['NA', 'na', 'N/A', 'n/a', 'NULL', 'null', 'None', 'none', 'nan', 'NaN', '#N/A']

cleaner = datacleaner.DataCleaner(
    null_values = default_null_values,
)

for ok in ('a','123', 123, 15.0, 2.66, -3.55, datetime.date(2017,3,5)):
    val = cleaner.clean(ok)
    assert ok is not None

for nullable in default_null_values:
    assert nullable is not None
    assert cleaner.clean(nullable) is None

additional = ['Toothpaste', -999, 0, 15.2, 'Woof', 'foo bar']
for ok in additional:
    val = cleaner.clean(ok)
    assert ok is not None

cleaner.add_null_values(additional)
for nullable in additional:
    assert nullable is not None
    assert cleaner.clean(nullable) is None

assert cleaner.clean(None) is None

#
# Examples of using translations
#

initial_translations = {
    -999:None,
    888:'Missing',
    '-999': 'N/A',
    '888': 5,
    None: 0,
    '777': 'INVALID string num not converting to num first',
    777: 'num convert is accurate',
    'xxx': 0,
}

cleaner = datacleaner.DataCleaner(
    translations = initial_translations
)
# this verifies the expected cases that types are converted before translations,
# so -999 and '-999' should relate to the same output (though we also dont trust order for hashes)
assert cleaner.clean('777') == 'num convert is accurate'
assert cleaner.clean(-999) == None
assert cleaner.clean('-999') == None
assert cleaner.clean(888) == 'Missing'
assert cleaner.clean('888') == 'Missing'
assert cleaner.clean(None) == 0
assert cleaner.clean('xxx') == 0

#
# test that adding translations after initialization works
assert cleaner.clean(999) == 999
cleaner.add_translations({999:None})
assert cleaner.clean(999) == None

basic_transliterations = [
    ('a','X'),
    [' ','_']
]
cleaner = datacleaner.DataCleaner(
    transliterations= basic_transliterations,
)

assert cleaner.clean('aaa') == 'XXX'
assert cleaner.clean('woof and bark') == 'woof_Xnd_bXrk'

#
# Time processing, requiring that the string ends up as a time object.
# Setting data_type means that the values are required to be None or time,
# and an error is thrown otherwise.  
#
cleaner = datacleaner.DataCleaner( data_type=datetime.time )

times = {
    '15:00': datetime.time(15,0),
    '2:00 pm': datetime.time(14,0),
    '2:00': datetime.time(2,0),
    '2:00PM': datetime.time(14,0),
    '0:00': datetime.time(0,0),
    '12:00': datetime.time(12,0),
    '12:00pm': datetime.time(12,0),
    '12:00 a.m.': datetime.time(0,0),
    '18:55:30.35': datetime.time(18,55,30, 350000),
    '18:55:30': datetime.time(18,55,30),
    '6:55:30 pm': datetime.time(18,55,30),
}

for raw, test in times.items():
    assert cleaner.clean(raw) == test


#
# Dates
#

dates = {
    '03-Aug-06': datetime.date(2006,8,3),
    '03-Aug-2006': datetime.date(2006,8,3),
    '3-Aug-06': datetime.date(2006,8,3),
    '3-Aug-2006': datetime.date(2006,8,3),
    '3-August-06': datetime.date(2006,8,3),
    '3-August-2006': datetime.date(2006,8,3),
    'Aug-03-06': datetime.date(2006,8,3),
    'Aug-03-2006': datetime.date(2006,8,3),
    'Monday, 3 of August 2006': datetime.date(2006,8,3),
    '03Aug06': datetime.date(2006,8,3),
    '03Aug2006': datetime.date(2006,8,3),
    '2006-08-03': datetime.date(2006,8,3),
    '20060803': datetime.date(2006,8,3),
    20060803: datetime.date(2006,8,3),
    '2006/08/03': datetime.date(2006,8,3),
    # month - day - year
    '08/03/06': datetime.date(2006,8,3),
    '08/03/2006': datetime.date(2006,8,3),
    '8/3/06': datetime.date(2006,8,3),
    '8/3/2006': datetime.date(2006,8,3),
    '12.18.97': datetime.date(1997,12,18),
    '12.25.2006': datetime.date(2006,12,25),
    '7-5-2000': datetime.date(2000,7,5),
}

cleaner.data_type = datetime.date
for raw, test in dates.items():
    assert cleaner.clean(raw) == test

datetimes = {
    '1994-11-05T08:15:30-05:00': datetime.datetime(
        1994, 11, 5, 8, 15, 30,
        tzinfo= datetime.timezone(datetime.timedelta(hours=-5))),
    '1994-11-05T13:15:30Z':datetime.datetime(
        1994, 11, 5, 13, 15, 30,
        tzinfo= datetime.timezone(datetime.timedelta(hours=0))),
    '1994-11-05T08:03:30-05:00': datetime.datetime(
        1994, 11, 5, 8, 3, 30,
        tzinfo= datetime.timezone(datetime.timedelta(hours=-5))),
    '1994-11-05T13:03:30Z':datetime.datetime(
        1994, 11, 5, 13, 3, 30,
        tzinfo= datetime.timezone(datetime.timedelta(hours=0))),
    '2006-08-03 18:55:30': datetime.datetime(2006,8,3,18,55,30),
    '03-Aug-2006 6:55:30 pm': datetime.datetime(2006,8,3,18,55,30),
}

cleaner.data_type = datetime.datetime
for raw, test in dates.items():
    assert cleaner.clean(raw) == test

Contributing

Contributions are collaboration is welcome. For major changes, please contact me in advance to discuss.

Please make sure to update tests for any contribution, as appropriate.

Author

Kevin Crouse. Copyright, 2019.

License

Apache 2.0

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