I have following tuple:
vertices = ([0,0],[0,0],[0,0]);
And on each loop I want to append the following list:
[x, y]
How should I approach it?
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1FYI you don't need to end your lines with a semi-colon in python.Ffisegydd– Ffisegydd2014-02-28 20:36:21 +00:00Commented Feb 28, 2014 at 20:36
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1It's a bit unclear what you're asking, could you give an example of what you want? How do you want them appending? etc?Ffisegydd– Ffisegydd2014-02-28 20:37:17 +00:00Commented Feb 28, 2014 at 20:37
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5 Answers
You can't append a list to a tuple because tuples are "immutable" (they can't be changed). It is however easy to append a tuple to a list:
vertices = [(0, 0), (0, 0), (0, 0)]
for x in range(10):
vertices.append((x, y))
You can add tuples together to create a new, longer tuple, but that strongly goes against the purpose of tuples, and will slow down as the number of elements gets larger. Using a list in this case is preferred.
Comments
You can't modify a tuple. You'll either need to replace the tuple with a new one containing the additional vertex, or change it to a list. A list is simply a modifiable tuple.
vertices = [[0,0],[0,0],[0,0]]
for ...:
vertices.append([x, y])
Comments
You can concatenate two tuples:
>>> vertices = ([0,0],[0,0],[0,0])
>>> lst = [10, 20]
>>> vertices = vertices + tuple([lst])
>>> vertices
([0, 0], [0, 0], [0, 0], [10, 20])
Comments
You probably want a list, as mentioned above. But if you really need a tuple, you can create a new tuple by concatenating tuples:
vertices = ([0,0],[0,0],[0,0])
for x in (1, 2):
for y in (3, 4):
vertices += ([x,y],)
Alternatively, and for more efficiency, use a list while you're building the tuple and convert it at the end:
vertices = ([0,0],[0,0],[0,0])
#...
vlist = list(vertices)
for x in (1, 2):
for y in (3, 4):
vlist.append([x, y])
vertices = tuple(vlist)
At the end of either one, vertices is:
([0, 0], [0, 0], [0, 0], [1, 3], [1, 4], [2, 3], [2, 4])
Comments
Not sure I understand you, but if you want to append x,y to each vertex you can do something like :
vertices = ([0,0],[0,0],[0,0])
for v in vertices:
v[0] += x
v[1] += y
Comments
