what do people use for 2D coordinates?

[John Hunter]

>>>>> "Andy" == Andy C <aayycc88 at hotmail.com> writes:

    Andy> You could use tuples or complex numbers (seems like a bit of
    Andy> a hack).  I saw somewhere it said that tuples are useful for
    Andy> coordinates.  But I haven't found a nice way to add
    Andy> coordinates, since + does concatenation on tuples.

If performance is not a major issue, and you want to be able to
generalize to arbitrary dimension, it is rather easy to write a python
class to do the work for you, implementing the special methods
__add__, __iadd__, __sub__ etc

class Coord:
    def __init__(self, tup):
        self.tup = tup

    def __add__(self, other):
        if len(other.tup) != len(self.tup): raise ValueError
        return Coord( [ x+y for x,y in zip(self.tup, other.tup)] )

    def __sub__(self, other):
        if len(other.tup) != len(self.tup): raise ValueError
        return Coord( [ x-y for x,y in zip(self.tup, other.tup)] )

    def __repr__(self):
        return str(self.tup)

    def __len__(self):
        return len(self.tup)

x = Coord( (1,2) )
y = Coord( (2,3) )

print x+y
print x-y

x = Coord( (1,2,4,5) )
y = Coord( (2,3,6,7) )

print x+y
print x-y

Of course, the Numeric module does element-wise array math by default,
do you might want to implement this in numeric if performance is an
issue.

John Hunter