jsimonrichard / micropython-ulab

a numpy-like fast vector module for micropython, circuitpython, and their derivatives

ulab

ulab is a numpy-like array manipulation library for micropython and CircuitPython. The module is written in C, defines compact containers for numerical data of one to four dimensions, and is fast. The library is a software-only standard micropython user module, i.e., it has no hardware dependencies, and can be compiled for any platform. The float implementation of micropython (float, or double) is automatically detected.

1. Supported functions
   1. ndarray
2. Usage
3. Customising the firmware
4. Finding help
5. Benchmarks
6. Firmware
7. Issues, contributing, and testing
   1. Testing

Supported functions

ndarray

ulab implements numpy's ndarray with the ==, !=, <, <=, >, >=, +, -, /, *, **, +=, -=, *=, /=, **= binary operators, and the len, ~, -, +, abs unary operators that operate element-wise. Type-aware ndarrays can be initialised from any micropython iterable, lists of iterables via the array constructor, or by means of the arange, concatenate, diag, eye, frombuffer, full, linspace, logspace, ones, or zeros functions.

ndarrays can be iterated on, and have a number of their own methods, such as flatten, itemsize, reshape, shape, size, strides, tobytes, and transpose.

Customising the firmware

In addition to the ndarray operators and methods, ulab defines a great number of functions that can take ndarrays or micropython iterables as their arguments. Most of the functions have been ported from numpy, but several are re-implementations of scipy features. For a complete list, see micropython-ulab!

If flash space is a concern, unnecessary functions can be excluded from the compiled firmware with pre-processor switches. In addition, ulab also has options for trading execution speed for firmware size. A thorough discussion on how the firmware can be customised can be found in the corresponding section of the user manual.

It is also possible to extend the library with arbitrary user-defined functions operating on numerical arrays, and add them to the namespace, as explaind in the programming manual.

Usage

ulab sports a numpy/scipy-compatible interface, which makes porting of CPython code straightforward. The following snippet should run equally well in micropython, or on a PC.

try:
    from ulab import numpy
    from ulab import scipy
except ImportError:
    import numpy
    import scipy.special

x = numpy.array([1, 2, 3])
scipy.special.erf(x)

Finding help

Documentation can be found on readthedocs under micropython-ulab, as well as at circuitpython-ulab. A number of practical examples are listed in Jeff Epler's excellent circuitpython-ulab overview.

Benchmarks

Representative numbers on performance can be found under ulab samples.

Firmware

Compiled firmware for many hardware platforms can be downloaded from Roberto Colistete's gitlab repository: for the pyboard, and for ESP8266. Since a number of features can be set in the firmware (threading, support for SD card, LEDs, user switch etc.), and it is impossible to create something that suits everyone, these releases should only be used for quick testing of ulab. Otherwise, compilation from the source is required with the appropriate settings, which are usually defined in the mpconfigboard.h file of the port in question.

ulab is also included in the following compiled micropython variants and derivatives:

1. CircuitPython for SAMD51 and nRF microcontrollers https://github.com/adafruit/circuitpython
2. MicroPython for K210 https://github.com/loboris/MicroPython_K210_LoBo
3. MaixPy https://github.com/sipeed/MaixPy
4. OpenMV https://github.com/openmv/openmv
5. pycom https://pycom.io/

Compiling

If you want to try the latest version of ulab on micropython or one of its forks, the firmware can be compiled from the source by following these steps:

UNIX port

Simply clone the ulab repository with

git clone https://github.com/v923z/micropython-ulab.git ulab

and then run

./build.sh

This command will clone micropython, and build the unix port automatically, as well as run the test scripts. If you want an interactive unix session, you can launch it in

ulab/micropython/ports/unix

STM-based boards

First, you have to clone the micropython repository by running

git clone https://github.com/micropython/micropython.git

on the command line. This will create a new repository with the name micropython. Staying there, clone the ulab repository with

git clone https://github.com/v923z/micropython-ulab.git ulab

If you don't have the cross-compiler installed, your might want to do that now, for instance on Linux by executing

sudo apt-get install gcc-arm-none-eabi

If this step was successful, you can try to run the make command in the port's directory as

make BOARD=PYBV11 USER_C_MODULES=../../../ulab all

which will prepare the firmware for pyboard.v.11. Similarly,

make BOARD=PYBD_SF6 USER_C_MODULES=../../../ulab all

will compile for the SF6 member of the PYBD series. If your target is unix, you don't need to specify the BOARD parameter.

Provided that you managed to compile the firmware, you would upload that by running either

dfu-util --alt 0 -D firmware.dfu

or

python pydfu.py -u firmware.dfu

In case you got stuck somewhere in the process, a bit more detailed instructions can be found under https://github.com/micropython/micropython/wiki/Getting-Started, and https://github.com/micropython/micropython/wiki/Pyboard-Firmware-Update.

ESP32-based boards

After version 1.14, micropython switched to cmake on the ESP32 port, thus breaking compatibility with user modules. ulab can, however, still be compiled with version 1.14. You can check out a particular version by pinning the release tag as

git clone https://github.com/micropython/micropython.git

cd ./micropython/
git checkout tags/v1.14

git submodule update --init
cd ./mpy-cross && make # build cross-compiler (required)

cd ./micropython/ports/esp32
make ESPIDF= # will display supported ESP-IDF commit hashes
# output should look like: """
# ...
# Supported git hash (v3.3): 9e70825d1e1cbf7988cf36981774300066580ea7
# Supported git hash (v4.0) (experimental): 4c81978a3e2220674a432a588292a4c860eef27b

Choose an ESPIDF version from one of the options printed by the previous command:

ESPIDF_VER=9e70825d1e1cbf7988cf36981774300066580ea7

# Download and prepare the SDK
git clone https://github.com/espressif/esp-idf.git $BUILD_DIR/esp-idf
cd ./esp-idf
git checkout $ESPIDF_VER
git submodule update --init --recursive # get idf submodules
pip install -r ./requirements.txt # install python reqs

Next, install the ESP32 compiler. If using an ESP-IDF version >= 4.x (chosen by $ESPIDF_VER above), this can be done by running . $BUILD_DIR/esp-idf/install.sh. Otherwise, (for version 3.x) run:

# for 64 bit linux
curl https://dl.espressif.com/dl/xtensa-esp32-elf-linux64-1.22.0-80-g6c4433a-5.2.0.tar.gz | tar xvz

# for 32 bit
# curl https://dl.espressif.com/dl/xtensa-esp32-elf-linux32-1.22.0-80-g6c4433a-5.2.0.tar.gz | tar xvz

# don't worry about adding to path; we'll specify that later

# also, see https://docs.espressif.com/projects/esp-idf/en/v3.3.2/get-started for more info

We can now clone the ulab repository

git clone https://github.com/v923z/micropython-ulab ulab

Finally, build the firmware:

cd ./micropython/ports/esp32
# temporarily add esp32 compiler to path
export PATH=xtensa-esp32-elf/bin:$PATH
export ESPIDF=esp-idf # req'd by Makefile
export BOARD=GENERIC # options are dirs in ./boards
export USER_C_MODULES=./ulab # include ulab in firmware

make submodules & make all

If it compiles without error, you can plug in your ESP32 via USB and then flash it with:

make erase && make deploy

Issues, contributing, and testing

If you find a problem with the code, please, raise an issue! An issue should address a single problem, and should contain a minimal code snippet that demonstrates the difference from the expected behaviour. Reducing a problem to the bare minimum significantly increases the chances of a quick fix.

Feature requests (porting a particular function from numpy or scipy) should also be posted at ulab issue.

Contributions of any kind are always welcome. If you feel like adding to the code, you can simply issue a pull request. If you do so, please, try to adhere to micropython's coding conventions.

However, you can also contribute to the documentation (preferably via the jupyter notebooks, or improve the tests.

Testing

If you decide to lend a hand with testing, here are the steps:

1. Write a test script that checks a particular function, or a set of related functions!
2. Drop this script in one of the folders in ulab tests!
3. Run the ./build.sh script in the root directory of ulab! This will clone the latest micropython, compile the firmware for unix, execute all scripts in the ulab/tests, and compare the results to those in the expected results files, which are also in ulab/tests, and have an extension .exp. In case you have a new snippet, i.e., you have no expected results file, or if the results differ from those in the expected file, a new expected file will be generated in the root directory. You should inspect the contents of this file, and if they are satisfactory, then the file can be moved to the ulab/tests folder, alongside your snippet.