Online array: A function that behaves like a NumPy array.

This package provides a class that mimics a multidimensional NumPy array. These arrays however, do not contain any data, all values are calculated on the fly instead. In this way, a function can be passed as an array to any function that only accepts arrays.

The function that gives the values of the online array is passed to the constructor of the class. The online array supports indexing, slicing and various arithmetic operations. Additionally, unbounded arrays can be defined.

Installation

Via PyPI:

pip install online-array

From source:

git clone https://github.com/jfjlaros/online-array.git
cd online-array
pip install .

Usage

Suppose we have the following function that we want to pass as an array to an other function:

def f(x, y):
    return x + y + 1

The easiest way to use the OnlineArray class is to pass a function and a shape to the convenience function online_array:

>>> from online_array import online_array
>>> a = online_array(f, (3, 3))

We now have a 3 by 3 online array. Values can be retrieved in the standard way by using indexes:

>>> a[1][2]
4
>>> a[1,2]
4

Slicing and stepping is supported:

>>> a[1:]
OnlineArray([[             2,              3,              4],
             [             3,              4,              5]])
>>> a[::2]
OnlineArray([[              1,               2,               3],
             [              3,               4,               5]])
>>> a[::2][1][0]
3

To create an unbounded array, the convenience function unbounded_online_array can be used:

>>> from online_array import unbounded_online_array
>>> a = unbounded_online_array(f)
>>> a[31415926535897932384626433][27182818284590452353602874]
58598744820488384738229308L

Finally, the class OnlineArray can be used directly.

>>> from online_array import OnlineArray
>>> help(OnlineArray)