https://github.com/mapbox/snuggs
Snuggs are s-expressions for Numpy
https://github.com/mapbox/snuggs
imagery pxm satellite
Last synced: 3 months ago
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Snuggs are s-expressions for Numpy
- Host: GitHub
- URL: https://github.com/mapbox/snuggs
- Owner: mapbox
- License: mit
- Created: 2015-02-12T01:35:37.000Z (over 10 years ago)
- Default Branch: master
- Last Pushed: 2023-11-25T13:56:06.000Z (almost 2 years ago)
- Last Synced: 2024-11-11T21:56:19.637Z (11 months ago)
- Topics: imagery, pxm, satellite
- Language: Python
- Homepage:
- Size: 39.1 KB
- Stars: 18
- Watchers: 114
- Forks: 6
- Open Issues: 3
-
Metadata Files:
- Readme: README.rst
- Changelog: CHANGES.txt
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.txt
- Authors: AUTHORS.txt
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README
======
snuggs
======
.. image:: https://travis-ci.org/mapbox/snuggs.svg?branch=master
:target: https://travis-ci.org/mapbox/snuggs
.. image:: https://coveralls.io/repos/mapbox/snuggs/badge.svg
:target: https://coveralls.io/r/mapbox/snuggs
Snuggs are s-expressions for Numpy
.. code-block:: python
>>> snuggs.eval("(+ (asarray 1 1) (asarray 2 2))")
array([3, 3])
Syntax
======
Snuggs wraps Numpy in expressions with the following syntax:
.. code-block::
expression = "(" (operator | function) *arg ")"
arg = expression | name | number | string
Examples
========
Addition of two numbers
-----------------------
.. code-block:: python
import snuggs
snuggs.eval('(+ 1 2)')
# 3
Multiplication of a number and an array
---------------------------------------
Arrays can be created using ``asarray``.
.. code-block:: python
snuggs.eval("(* 3.5 (asarray 1 1))")
# array([ 3.5, 3.5])
Evaluation context
------------------
Expressions can also refer by name to arrays in a local context.
.. code-block:: python
snuggs.eval("(+ (asarray 1 1) b)", b=np.array([2, 2]))
# array([3, 3])
This local context may be provided using keyword arguments (e.g.,
``b=np.array([2, 2])``), or by passing a dictionary that stores
the keys and associated array values. Passing a dictionary, specifically
an ``OrderedDict``, is important when using a function or operator that
references the order in which values have been provided. For example,
the ``read`` function will lookup the `i-th` value passed:
.. code-block:: python
ctx = OrderedDict((
('a', np.array([5, 5])),
('b', np.array([2, 2]))
))
snuggs.eval("(- (read 1) (read 2))", ctx)
# array([3, 3])
Functions and operators
=======================
Arithmetic (``* + / -``) and logical (``< <= == != >= > & |``) operators are
available. Members of the ``numpy`` module such as ``asarray()``, ``mean()``,
and ``where()`` are also available.
.. code-block:: python
snuggs.eval("(mean (asarray 1 2 4))")
# 2.3333333333333335
.. code-block:: python
snuggs.eval("(where (& tt tf) 1 0)",
tt=numpy.array([True, True]),
tf=numpy.array([True, False]))
# array([1, 0])
Higher-order functions
======================
New in snuggs 1.1 are higher-order functions ``map`` and ``partial``.
.. code-block:: python
snuggs.eval("((partial * 2) 2)")
# 4
snuggs.eval('(asarray (map (partial * 2) (asarray 1 2 3)))')
# array([2, 4, 6])
Performance notes
=================
Snuggs makes simple calculator programs possible. None of the optimizations
of, e.g., `numexpr `__ (multithreading,
elimination of temporary data, etc) are currently available.
If you're looking to combine Numpy with a more complete Lisp, see
`Hy `__:
.. code-block:: clojure
=> (import numpy)
=> (* 2 (.asarray numpy [1 2 3]))
array([2, 4, 6])