fzeiser
commented
5 years ago 
So, subclassing will work. But without a wiser implementation than mine (which was basically copied from the numpy instructions above), the calculations will take more time. Maybe implement in Cython?
import numpy as np
import timeit
class MyClass(np.ndarray):
def __new__(cls, data, Earr1=None, Earr2=None):
obj = np.asarray(data).view(cls)
obj.Earr1 = Earr1
obj.Earr2 = Earr2
return obj
def __array_finalize__(self, obj):
if obj is None: return
self.Earr1 = getattr(obj, 'Earr1', None)
self.Earr2 = getattr(obj, 'Earr2', None)
class MyClassGetItem(np.ndarray):
def __new__(cls, data, Earr1=None, Earr2=None):
obj = np.asarray(data).view(cls)
obj.Earr1 = Earr1
obj.Earr2 = Earr2
return obj
def __array_finalize__(self, obj):
self.Earr1 = getattr(obj, 'Earr1', None)
self.Earr2 = getattr(obj, 'Earr2', None)
def __getitem__(self, item):
ret = super(MyClassGetItem, self).__getitem__(item)
# need this, such that single entries still keep a energy calibration
ret = MyClassGetItem(ret,Earr1=self.Earr1, Earr2=self.Earr2)
if self.Earr1 is not None and isinstance(item[0], (slice, int)):
ret.Earr1 = self.Earr1.__getitem__(item[0])
if len(item)==2:
if self.Earr2 is not None and isinstance(item[1], (slice, int)):
ret.Earr2 = self.Earr2.__getitem__(item[1])
return ret
class OsloClass():
"""
The matrix class stores matrices along with calibration and energy axis arrays.
"""
def __init__(self, matrix=None, Earr1=None, Earr2=None):
"""
Initialise the class. There is the option to initialise
it in an empty state. In that case, all class variables will be None.
It can be filled later using the load() method.
"""
self.matrix = matrix
self.Earr1 = Earr1
self.Earr2 = Earr2
def print_timing(cmd):
t = timeit.timeit(cmd,globals=globals(), number=int(1e6))
print (t)
arr = np.arange(5)
arr2d = np.array([arr,arr,arr-3,arr+7,arr+3])
# numpy result
print_timing('np.sqrt(arr2d)')
# 2.23
print_timing('np.sqrt(arr2d)[2,2]')
# 2.48
# MyClass
a = MyClass(arr2d, Earr1=arr, Earr2=-arr)
print_timing('np.sqrt(a)')
# 3.73
# 3.95
# MyClass with the GetItem attribute
a = MyClassGetItem(arr2d, Earr1=arr, Earr2=-arr)
print_timing('np.sqrt(a)')
# 3.74
print_timing('np.sqrt(a)[2,2]')
# 9.75
Wouldn't it be good to have the matrix class be a subclass of
ndarray? Then you can run allnumpyfunctions eg. on theom.firstgenobject itself, instead of having to callom.firstgen.matrixevery time.For implementation: https://docs.scipy.org/doc/numpy-1.13.0/user/basics.subclassing.html#slightly-more-realistic-example-attribute-added-to-existing-array
Note that we should change the name from
matrixto something else then, in order to not confuse it withnumpy.matrix. Eg. the class could be calledOsloMatrixor maybe ratherOsloArray