np-struct 0.0.1

user friendly interface for NumPy structured arrays

np-struct

np-struct extends structured arrays in NumPy to be a bit more user friendly and intuitive, with added support for transferring structured arrays across serial or socket interfaces.

Structured arrays are built to mirror the struct typedef in C/C++, but can be used for any complicated data structure. They behave similar to standard arrays, but support mixed data types, labeling, and unequal length arrays. Arrays are easily written or loaded from disk in the standard .npy binary format.

Installation

pip install np-struct

Usage

import np_struct 

Create a c-style structure with Numpy types.

from np_struct import Struct
import numpy as np

class example(Struct):
    data1 = np.uint32()
    data2 = np.complex128([0]*3)

Structures can be initialized with arbitrary shapes by using the shape kwarg:

ex = example(shape = (3,), byte_order='>')
ex[0].data2 = 1 + 2j

>>> ex
Struct example: (3,)
[
    psize:  uint16[0]
    data1:  uint32[0]
    data2:  complex128[1.+2.j 1.+2.j 1.+2.j]
]
...
[
    psize:  uint16[0]
    data1:  uint32[0]
    data2:  complex128[0.+0.j 0.+0.j 0.+0.j]
]

Members can also be initialized by passing in their name to the constructor with an inital value.

>> example(data2 = np.zeros(shape=(3,2)))
Struct example: 
    psize:  uint16[0]
    data1:  uint32[0]
    data2:  complex128[[0.+0.j 0.+0.j]
	       [0.+0.j 0.+0.j]
	       [0.+0.j 0.+0.j]]

The structure inherits from np.ndarray and supports all math functions that a normal structured array does. To cast as a standard numpy array:

>> ex2.view(np.ndarray)
array([([0], [0], [[0.+0.j, 0.+0.j], [0.+0.j, 0.+0.j], [0.+0.j, 0.+0.j]])],
      dtype=[('psize', '<u2', (1,)), ('data1', '<u4', (1,)), ('data2', '<c16', (3, 2))])

Nested structures are also supported:

class nested(Struct):
    field1 = example()
    field2 = example()

n = nested()
n.field1.data2 += j*np.pi

>> n
Struct nested: 
    field1:  Struct example: 
              psize:  uint16[0]
              data1:  uint32[0]
              data2:  complex128[0.+3.14159265j 0.+3.14159265j 0.+3.14159265j]
    field2:  Struct example: 
              psize:  uint16[0]
              data1:  uint32[0]
              data2:  complex128[0.+0.j 0.+0.j 0.+0.j]

Examples:

Transfering structures over an interface
Labeled arrays

License

np-struct is licensed under the MIT License.