pyroaring 0.2.1

Fast and lightweight set for unsigned 32 bits integers.

An efficient and light-weight ordered set of 32 bits integers. This is a Python wrapper for the C library CRoaring.

The wrapping used to be done with Ctypes. We recently switched to Cython for the following reasons:

• Much better performances for short function calls (e.g. addition/deletion of a single element).

• Easier installation, no need to install manually the C library, it is now distributed with PyRoaring.

• Extensibility, it will be easier to write efficient codes with Cython (e.g. some data structures based on roaring bitmaps).

If for some reason you wish to keep using the old version, based on Ctypes, use PyRoaring 0.0.7.

Requirements

• Environment like Linux and MacOS

• Python 2.7, or Python 3.4 or better

• A recent C compiler like GCC

• The package manager pip

• The Python package hypothesis (optional, for testing)

• The Python package Cython (optional, for compiling pyroaring from the sources)

• The Python package wheel (optional, to build a wheel for the library)

Installation

To install pyroaring on your local account, use the following command:

pip install pyroaring --user # installs PyRoaringBitMap

For a system-wide installation, use the following command:

pip install pyroaring

Naturally, the latter may require superuser rights (consider prefixing the commands by sudo).

If you want to use Python 3 and your system defaults on Python 2.7, you may need to adjust the above commands, e.g., replace pip by pip3.

Manual compilation / installation

If you want to compile (and install) pyroaring by yourself, for instance to modify the Cython sources or because you do not have pip, follow these steps. Note that the Python package Cython is required.

Clone this repository.

git clone https://github.com/Ezibenroc/PyRoaringBitMap.git
cd PyRoaringBitMap
git submodule init && git submodule update

Build pyroaring locally, e.g. to test a new feature you made.

python setup.py build_ext -i
python test.py # run the tests, optionnal but recommended

Install pyroaring (use this if you do not have pip).

python setup.py install # may require superuser rights, add option --user if you wish to install it on your local account

Package pyroaring.

python setup.py sdist
pip install dist/pyroaring-0.1.?.tar.gz # optionnal, to install the package

Build a wheel.

python setup.py bdist_wheel

For all the above commands, two environment variables can be used to control the compilation.

• DEBUG=1 to build pyroaring in debug mode.

• ARCHI=<cpu-type> to build pyroaring for the given platform. The platform may be any keyword given to the -march option of gcc (see the documentation). Note that cross-compiling for a 32-bit architecture from a 64-bit architecture is not supported.

Example of use:

DEBUG=1 ARCHI=x86-64 python setup.py build_ext

Utilization

First, you can run the tests to make sure everything is ok:

pip install hypothesis --user
python test.py

Note: you can define the environment variable HYPOTHESIS_PROFILE to debug to print every values, or ci to perform more tests (warning: very long). For instance:

HYPOTHESIS_PROFILE=debug ./test.py

You can use a bitmap nearly as the classical Python set in your code:

from pyroaring import BitMap
bm1 = BitMap()
bm1.add(3)
bm1.add(18)
bm2 = BitMap([3, 27, 42])
print("bm1       = %s" % bm1)
print("bm2       = %s" % bm2)
print("bm1 & bm2 = %s" % (bm1&bm2))
print("bm1 | bm2 = %s" % (bm1|bm2))

Output:

bm1       = BitMap([3, 18])
bm2       = BitMap([3, 27, 42])
bm1 & bm2 = BitMap([3])
bm1 | bm2 = BitMap([3, 18, 27, 42])

Benchmark

Pyroaring is compared with the built-in set and other implementations:

• A Python wrapper of CRoaring called python-croaring

• A Cython implementation of Roaring bitmaps called roaringbitmap

• A Python implemenntation of ordered sets called sortedcontainers

The script quick_bench.py measures the time of different set operations. It uses randomly generated sets of size 1e6 and density 0.125. For each operation, the average time (in seconds) of 30 tests is reported.

The results have been obtained with:

• CPU Intel Xeon CPU E5-2630 v3

• CPython version 3.5.3

• gcc version 6.3.0

• Cython version 0.28.3

• pyroaring commit dcf448a

• python-croaring commit 3aa61dd

• roaringbitmap commit 502d78d

• sortedcontainers commit 7d6a28c

operation	pyroaring	python-croaring	roaringbitmap	set	sortedcontainers
range constructor	3.09e-04	1.48e-04	8.72e-05	7.29e-02	2.08e-01
ordered list constructor	3.45e-02	6.93e-02	1.45e-01	1.86e-01	5.74e-01
list constructor	1.23e-01	1.33e-01	1.55e-01	1.12e-01	5.12e-01
ordered array constructor	5.06e-03	6.42e-03	2.89e-01	9.82e-02	3.01e-01
array constructor	1.13e-01	1.18e-01	4.63e-01	1.45e-01	5.08e-01
element addition	3.08e-07	8.26e-07	2.21e-07	1.50e-07	1.18e-06
element removal	3.44e-07	8.17e-07	2.61e-07	1.78e-07	4.26e-07
membership test	1.24e-07	1.00e-06	1.50e-07	1.00e-07	5.72e-07
union	1.61e-04	1.96e-04	1.44e-04	2.15e-01	1.11e+00
intersection	9.08e-04	9.48e-04	9.26e-04	5.22e-02	1.65e-01
difference	1.57e-04	1.97e-04	1.43e-04	1.56e-01	4.84e-01
symmetric diference	1.62e-04	2.01e-04	1.44e-04	2.62e-01	9.13e-01
equality test	7.80e-05	7.82e-05	5.89e-05	1.81e-02	1.81e-02
subset test	7.92e-05	8.12e-05	8.22e-05	1.81e-02	1.81e-02
conversion to list	4.71e-02	2.78e-01	4.35e-02	5.77e-02	5.32e-02
pickle dump & load	4.02e-04	6.27e-04	5.08e-04	2.41e-01	5.75e-01
“naive” conversion to array	5.12e-02	2.92e-01	4.75e-02	1.20e-01	1.18e-01
“optimized” conversion to array	1.27e-03	3.40e-02	nan	nan	nan
selection	1.77e-06	5.33e-05	1.14e-06	nan	1.64e-05
contiguous slice	9.38e-05	9.51e-05	6.99e-05	nan	2.04e-02
slice	2.88e-03	3.04e-01	1.00e-01	nan	4.74e-01
small slice	8.93e-05	3.00e-01	3.60e-03	nan	1.79e-02