Python: References, dictionaries and lists

I've just started writing with Python and still getting
used with references and where they are and aren't used.

I've written the following
code:

dummyList =
            self.getSprayLocation(heading, "left")
self.points['leftLeft'][0] =
            self.armLocations['leftX'] -
            self.mmToCoor(dummyList[0])
self.points['leftLeft'][1] =
            self.armLocations['leftY'] -
            self.mmToCoor(dummyList[1])
self.points['rightLeft'][0] =
            self.armLocations['leftX'] +
            self.mmToCoor(dummyList[0])
self.points['rightLeft'][1] =
            self.armLocations['leftY'] + self.mmToCoor(dummyList[1])
dummyList =
            self.getSprayLocation(heading,
            "mid")
print(self.points['leftLeft'][1])


self.points['leftMid'][0]
            = self.armLocations['midX'] -
            self.mmToCoor(dummyList[0])
self.points['leftMid'][1] =
            self.armLocations['midY'] -
            self.mmToCoor(dummyList[1])
self.points['rightMid'][0] =
            self.armLocations['midX'] +
            self.mmToCoor(dummyList[0])
self.points['rightMid'][1] =
            self.armLocations['midY'] +
            self.mmToCoor(dummyList[1])
print(self.points['leftLeft'][1])

dummyList
            = self.getSprayLocation(heading, "right")
self.points['leftRight'][0] =
            self.armLocations['rightX'] -
            self.mmToCoor(dummyList[0])
self.points['leftRight'][1] =
            self.armLocations['rightY'] -
            self.mmToCoor(dummyList[1])

self.points['rightRight'][0] =
            self.armLocations['rightX'] +
            self.mmToCoor(dummyList[0])
self.points['rightRight'][1] =
            self.armLocations['rightY'] +
            self.mmToCoor(dummyList[1])
print(self.points['leftLeft'][1])

It's
in a Class, where 'points' is a dictionary containing a
list:

coordinate = [0,
            0]
points = {'leftLeft':coordinate, 'rightLeft':coordinate,
            'leftMid':coordinate, 'rightMid':coordinate, 'leftRight':coordinate,
            'rightRight':coordinate}

Note
that after every block of code I print the ['leftLeft'][0] value. I expect this value
not to change when I don't write to this key in the
dictionary.

But when I run this code, this is
the
output

51.861101789
51.8611355556
51.8611192766

Which
means the value is changed. In fact, all 'leftX' entries are the same and all 'rightX'
entries are the same.

Now I think it has
something to do with the references, but I haven't come up with a solution for this yet.

Thanks for your
help!

---

Edit:

Thanks to JoshuaF I found that the reference was in the

coordinate = [0,
            0]
points = {'leftLeft':coordinate, 'rightLeft':coordinate,
            'leftMid':coordinate, 'rightMid':coordinate, 'leftRight':coordinate,
            'rightRight':coordinate}

Block.
'coordinate' was the same 'coordinate' everywhere. The following fixes
this:

coordinate = [0,
            0]
points = {'leftLeft':coordinate[:], 'rightLeft':coordinate[:],
            'leftMid':coordinate[:], 'rightMid':coordinate[:], 'leftRight':coordinate[:],
            'rightRight':coordinate[:]}

I
know the [:] has got something to do with references and lists. But
what?

---

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