Fast array processing functions
Project description
- Version:
- 3.1.0 for 2017-10-12
- Copyright:
- 2014 - 2017
- License:
This document may be distributed under the Apache 2.0 License.
- Language:
Python 3.5 or later
Introduction
The arrayfunc module provides high speed array processing functions for use with the standard Python array module. These functions are patterned after the functions in the standard Python Itertools module together with some additional ones from other sources.
The purpose of these functions is to perform mathematical calculations on arrays faster than using native Python.
Functions
Summary
The functions fall into several categories.
Filling Arrays
Function |
Description |
|---|---|
count |
Fill an array with evenly spaced values using a start and step values. |
cycle |
Fill an array with evenly spaced values using a start, stop, and step values, and repeat until the array is filled. |
repeat |
Fill an array with a specified value. |
Filtering Arrays
Function |
Description |
|---|---|
afilter |
Select values from an array based on a boolean criteria. |
compress |
Select values from an array based on another array of boolean values. |
dropwhile |
Select values from an array starting from where a selected criteria fails and proceding to the end. |
takewhile |
Like dropwhile, but starts from the beginning and stops when the criteria fails. |
Examining and Searching Arrays
Function |
Description |
|---|---|
aany |
Returns True if any element in an array meets the selected criteria. |
aall |
Returns True if all element in an array meet the selected criteria. |
amax |
Returns the maximum value in the array. |
amin |
Returns the minimum value in the array. |
findindex |
Returns the index of the first value in an array to meet the specified criteria. |
findindices |
Searches an array for the array indices which meet the specified criteria and writes the results to a second array. Also returns the number of matches found. |
Operating on Arrays
Function |
Description |
|---|---|
amap |
Apply an operator to each element of an array, together with an optional second parameter (for operators taking two parameters). The results are written to a second array. |
amapi |
Like amap, but the results are written in place to the input array. |
starmap |
Like amap, but where a second array acts as the second parameter. The results are written to an output array. |
starmapi |
Like starmap, but the results are written in place to the first input array. |
asum |
Calculate the arithmetic sum of an array. |
acalc |
Calculate arbitrary equations over an array. |
Amap and amapi support more than 70 different operations. Starmap and starmapi support more than two dozen different operations. ACalc supports more than 50 operations.
Data Conversion
Function |
Description |
|---|---|
convert |
Convert arrays between data types. The data will be converted into the form required by the output array. |
Attributes
In addition to functions, a set of attributes are provided representing the platform specific maximum and minimum numerical values for each array type. These attributes are part of the “arraylimits” module.
Supported Array Types
Arrayfunc supports all standard Python 3.x array types, as well as the ‘bytes’ type.
Performance
Performance will vary depending on the function, operation, array data type used, and whether overflow checking is enabled.
Average performance increase for amap is 80 times faster than native Python. Functions other than amap, starmap, and acalc average is 50 times faster than native Python. However, some functions and operations may be more than 200 to 300 times faster than native Python.
Detailed performance figures are listed in the documentation.
Platform support
Arrayfunc is written in ‘C’ and uses the standard C libraries to implement the underlying math functions. Arrayfunc has been tested on the following platforms.
OS |
Bits |
Compiler |
Python Version Tested |
|---|---|---|---|
Ubuntu 16.04 LTS |
64 bit |
GCC |
3.5 |
Debian 9 |
32 bit |
GCC |
3.5 |
Debian 9 |
64 bit |
GCC |
3.5 |
FreeBSD 11 |
64 bit |
LLVM |
3.5 |
MS Windows 10 |
64 bit |
MS Visual Studio C 2015 |
3.6 |
Installation
Please note that this is a Python 3 package. To install using Pip, you will need (with Debian package in brackets):
The appropriate C compiler and header files (gcc and build-essential).
The Python3 development headers (python3-dev).
Pip3 together with the corresponding Setuptools (python3-pip).
example:
# Install from PyPI. pip3 install arrayfunc # Install from a local copy of the source package (Linux). pip3 install --no-index --find-links=. arrayfunc # Windows seems to use "pip" instead of "pip3" for some reason. pip install arrayfunc
Release History
1.0.0 - First release.
1.1.0 - Added support for math constants math.pi and math.e.
- 2.0.0 - Many changes. Updated MS Windows support to 3.6 and latest compiler.
This in turn brought the Windows version up to feature parity with the other versions. Changed supported MS Windows version from 32 bit to 64 bit. Added SIMD support for some functions which provided a significant performance for those affected. Updated supported versions of Debian and FreeBSD to current releases.
2.1.1 - Fixed missing header files in PyPI package. No functional changes.
3.0.0 - Changed package format to “Wheel” files. No functional changes.
3.1.0 - Added log2 to amap, amapi, and acalc.
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