I want to use numpy array on galois field (GF4). so, I set GF4 class to array elements. It works on array + integer calculation but it dosen't works on array + array calculation.
import numpy
class GF4(object):
"""class for galois field"""
def __init__(self, number):
self.number = number
self.__addL__ = ((0,1,2,3),(1,0,3,2),(2,3,0,1),(3,2,1,0))
self.__mulL__ = ((0,0,0,0),(0,1,2,3),(0,2,3,1),(0,3,1,2))
def __add__(self, x):
return self.__addL__[self.number][x]
def __mul__(self, x):
return self.__mulL__[self.number][x]
def __sub__(self, x):
return self.__addL__[self.number][x]
def __div__(self, x):
return self.__mulL__[self.number][x]
def __repr__(self):
return str(self.number)
a = numpy.array([GF4(numpy.random.randint(4)) for i in range(18)]).reshape(3,6)
b = numpy.array([GF4(numpy.random.randint(4)) for i in range(18)]).reshape(3,6)
""""
In [261]: a
Out[261]:
array([[1, 1, 2, 0, 2, 1],
[0, 3, 1, 0, 3, 1],
[1, 2, 0, 3, 2, 1]], dtype=object)
In [262]: b
Out[262]:
array([[0, 0, 3, 1, 0, 0],
[0, 1, 0, 1, 1, 1],
[3, 2, 2, 0, 2, 0]], dtype=object)
In [263]: a+1
Out[263]:
array([[0, 0, 3, 1, 3, 0],
[1, 2, 0, 1, 2, 0],
[0, 3, 1, 2, 3, 0]], dtype=object)
In [264]: a+b
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-264-f1d53b280433> in <module>()
----> 1 a+b
<ipython-input-260-0679b73b59a4> in __add__(self, x)
8 self.__mulL__ = ((0,0,0,0),(0,1,2,3),(0,2,3,1),(0,3,1,2))
9 def __add__(self, x):
---> 10 return self.__addL__[self.number][x]
11 def __mul__(self, x):
12 return self.__mulL__[self.number][x]
TypeError: tuple indices must be integers, not GF4
"""
But it also works on array and array * integer caliculation.
"""
In [265]: a+b*1
Out[265]:
array([[1, 1, 1, 1, 2, 1],
[0, 2, 1, 1, 2, 0],
[2, 0, 2, 3, 0, 1]], dtype=object)
"""
How should I correct the following codes? I want to use my class GF4.
The problem is that Python doesn't know how to index tuples when x
is a GF4
object. You could do something like this to solve that:
def __add__(self, x):
if isinstance(x, GF4):
x = x.number
return self.__addL__[self.number][x]
There is another potential issue you may want to look at, that explains why your third test case works: when you add an int
to a GF4
what gets returned is an int, not a GF4
. Unless this is a desired behavior, I think your code for __add__
should be more like:
def __add__(self, x):
if isinstance(x, GF4):
x = x.number
return GF4(self.__addL__[self.number][x])
You may want to think over all the possibilities and decide if youneed to build more safeguards and throw a few errors of your own, e.g. what should be the return if you try to add a float
to a GF4
?
来源:https://stackoverflow.com/questions/17044064/how-to-calculate-numpy-arrays-on-galois-field