Super-fast and clean conversions to numbers.
fastnumbers is a module with the following three objectives:
- Provide drop-in replacements for the Python built-in
floatthat on average are up to 2x faster. These functions should behave identically to the Python built-ins except for a few specific corner-cases as mentioned in the API documentation.
- Provide a set of convenience functions that wrap the above
floatreplacements and provides easy, concise, powerful, fast and flexible error handling.
- Provide a set of functions that can be used to rapidly identify if an input could be converted to int or float.
The below examples showcase the
fast_float function, which is
a fast conversion function with error-handling.
Please see the
for other functions that are available from
>>> from fastnumbers import fast_float, float as fnfloat >>> # Convert string to a float >>> fast_float('56.07') 56.07 >>> # Unconvertable string returned as-is by default >>> fast_float('bad input') 'bad input' >>> # Unconvertable strings can trigger a default value >>> fast_float('bad input', default=0) 0 >>> # 'default' is also the first optional positional arg >>> fast_float('bad input', 0) 0 >>> # Integers are converted to floats >>> fast_float(54) 54.0 >>> # One can ask inf or nan to be substituted with another value >>> fast_float('nan') nan >>> fast_float('nan', nan=0.0) 0.0 >>> fast_float(float('nan'), nan=0.0) 0.0 >>> fast_float('56.07', nan=0.0) 56.07 >>> # The default built-in float behavior can be triggered with >>> # "raise_on_invalid" set to True. >>> fast_float('bad input', raise_on_invalid=True) #doctest: +IGNORE_EXCEPTION_DETAIL Traceback (most recent call last): ... ValueError: invalid literal for float(): bad input >>> # A key function can be used to return an alternate value for invalid input >>> fast_float('bad input', key=len) 9 >>> fast_float(54, key=len) 54.0 >>> # Single unicode characters can be converted. >>> fast_float(u'\u2164') # Roman numeral 5 (V) 5.0 >>> fast_float(u'\u2466') # 7 enclosed in a circle 7.0
NOTE: If you need locale-dependent conversions, supply the
function of your choice to
import locale locale.setlocale(locale.LC_ALL, 'de_DE.UTF-8') print(atof('468,5', func=fast_float)) # Prints 468.5
Just how much faster is
fastnumbers than a pure python implementation?
Please see the following Jupyter notebooks for timing information on various Python versions.
$ pip install fastnumbers
How to Run Tests
Please note that
fastnumbers is NOT set-up to support
python setup.py test.
The recommended way to run tests is with tox. Suppose you want to run tests for Python 3.6 - you can run tests by simply executing the following:
$ tox -e py36
tox will create virtual a virtual environment for your tests and install all the
needed testing requirements for you.
If you want to run testing on all of Python 2.7, 3.4, 3.5, 3.6, and 3.7 you can simply execute
If you do not wish to use
tox, you can install the testing dependencies and run the
tests manually using pytest -
Pipfile for use with pipenv that
makes it easy for you to install the testing dependencies:
$ pipenv install --skip-lock --dev $ pipenv install --skip-lock -e . $ pipenv run pytest
Seth M. Morton
Please visit the changelog.