I am trying creating an NumPy array filled with an object, and I was wondering if there was a way I could broadcast to the entire array for each object to do something.
Code:
class player:
def __init__(self,num = 5):
self.num = num
def printnum():
print(self.num)
...
objs = np.array([player(5),player(6)],dtype=Object)
objs.printnum()
As it stands this returns an error. I have tried changing the dtype to: _object as per the manual, but nothing seems to work.
A numpy array of objects does not inherit the methods of that object. ndarray methods in general act on the entire array
This does not work for built-in types either, e.g.:
In [122]: import numpy as np
In [123]: n = 4.0
In [124]: a = np.arange(n)
In [125]: n.is_integer()
Out[125]: True
In [126]: a.is_integer()
---------------------------------------------------------------------------
AttributeError: 'numpy.ndarray' object has no attribute 'is_integer'
Numpy broadcasting is done with element-wise operators, for example addition:
In [127]: n
Out[127]: 4.0
In [128]: a
Out[128]: array([ 0., 1., 2., 3.])
In [129]: n + a
Out[129]: array([ 4., 5., 6., 7.])
If you want to basically call print on all the elements in your array, you could simply redefine the .__repr__() method which is called by print. I would caution you that you will lose information by overriding the method.
In [148]: class player:
.....: def __init__(self, num=5):
.....: self.num = num
.....: def __repr__(self):
.....: return str(self.num)
.....:
In [149]: objs = np.array([player(5), player(6)])
In [150]: objs
Out[150]: array([5, 6], dtype=object)
In [151]: print objs
[5 6]
Even though it looks like it, this is not the same as np.array([5,6]) though:
In [152]: objs * 3
----------------------
TypeError: unsupported operand type(s) for *: 'instance' and 'int'
And there you can see the disadvantage of overriding __repr__.
The simpler way to do this is to use your current printnum() method, but call it in a loop:
In [164]: class player:
.....: def __init__(self, num=5):
.....: self.num = num
.....: def printnum(self):
.....: print(self.num)
.....:
In [165]: for p in objs:
.....: p.printnum()
.....:
5
6
Or, perhaps define your method to return a string rather than print one, then make a list comprehension:
In [169]: class player:
.....: def __init__(self, num=5):
.....: self.num = num
.....: def printnum(self):
.....: return str(self.num)
.....:
In [170]: objs = np.array([player(5), player(6)])
In [171]: [p.printnum() for p in objs]
Out[171]: ['5', '6']
Couple typos in your code: printnum() needs self arg, and Object->object
class player:
def __init__(self, num=5):
self.num = num
def printnum(self):
print(self.num)
objs = np.array([player(5),player(6)], dtype=object)
# It's not a "broadcast" (what you mean is map), but it has the same result
# plus it's pythonic (explicit + readable)
for o in objs:
o.printnum()
It looks like what you really want to do is create a generator object. Google python generator yield and you'll get some examples like this
