Got the goal of adding functionalities to an existent project - IntervalMap project !. As the internal operators ( __add__
, __mul__
, etc.) aren't implemented yet, need to subscribe them.
This is the code I've implemented at __add__
builtin to perform intervalmap addition.
# ...
def __add__(self, other):
"""
a = x + y
"""
aux = intervalmap()
if isinstance(other, self.__class__):
ruler = self._bounds + other._bounds
ruler = map(ruler.sort(), ruler)
for i, x in enumerate(ruler):
if i > 0:
_slice = slice(ruler[i-1], x, None)
point = (_slice.start + _slice.stop) / 2.0
if self[point] is None:
aux.__setitem__(_slice, other[point])
elif other[point] is None:
aux.__setitem__(_slice, self[point])
else:
aux.__setitem__(_slice, self[point] + other[point])
if isinstance(other, (int,float)):
for i, x in enumerate(self._bounds):
if i > 0:
point = (self._bounds[i-1] + x) / 2
aux[self._bounds[i-1]:x] = self[point] + other
return aux
# ...
if __name__ == '__main__':
x = intervalmap()
y = intervalmap()
x[1:2] = 6
x[4:5] = 1
x[7:8] = 5
y[0:3] = 4
y[3:6] = 2
y[6:9] = 11
print x
print y
Output
>>> {[1, 2] => 6, [4, 5] => 1, [7, 8] => 5}
>>> {[0, 3] => 4, [3, 6] => 2, [6, 9] => 11}
a = x + y
b = y + x
print a
print b
>>> {[0, 1] => 4, [1, 2] => 10, [2, 3] => 4, [3, 4] => 2, [4, 5] => 3, [5, 6] => 2, [6, 7] => 11, [7, 8] => 16, [8, 9] => 11}
>>> {[0, 1] => 4, [1, 2] => 10, [2, 3] => 4, [3, 4] => 2, [4, 5] => 3, [5, 6] => 2, [6, 7] => 11, [7, 8] => 16, [8, 9] => 11}
a = y + 2
print a
b = 2 + y
print b
>>> {[0, 3] => 6, [3, 6] => 4, [6, 9] => 13}
Traceback (most recent call last): File "/home/pc/workspace/simulador-mti/source/y.py", line 73, in <module> b = 2 + y
TypeError: unsupported operand type(s) for +: 'int' and 'IntervalMap'
Want to be abble to add a constant number to an intervalmap object no matter the position, right or left operand. How can I add a number as left operand?
By the way, do anyone see a way to do this in a generic way? like passing to an update function x.update(y, lambda x,y: x+y)
to perform the same thing.
You can define __radd__
method in addition to __add__
.
To paraphrase a documentation :
__radd__ is only called if the left operand does not support the add operation and the operands are of different types. [2] For instance, to evaluate the expression x + y, where y is an instance of a class that has __radd__() method, y.__radd__(x) is called if x.__add__(y) returns NotImplemented.
It should look like this:
class X(object):
def __init__(self, val):
self.val = val
def __add__(self, other):
if isinstance(other, X):
return X(self.val + other.val)
else:
return X(self.val + other)
def __radd__(self, other):
return self.__add__(other)
X(3) + 4 # calls `__add__`
4 + X(3) # calls `__radd__`
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