Hello! Is there a way to join two lists? For example, v=[1,2,3]; w=[4,5,6];
how can I obtain the list z=[1,2,3,4,5,6]? Thank you very much, Francesco
You can simply add them:
sage: a = [1,2,3]
sage: b = [4,5,6]
sage: z = a+b
sage: z
[1, 2, 3, 4, 5, 6]Note that you can't subtract them, though:
sage: a-b
Traceback (most recent call last):
...
TypeError: unsupported operand type(s) for -: 'list' and 'list'This is basically because it's not obvious what to do with [1,2,3]-[4,5], and a fundamental Python principle is to resist the temptation to guess in the face of ambiguity.
It might be helpful to work through a Python tutorial.
In other words, lists form a semigroup. If you want subtraction you have to go through the Grothendiek construction....
In fact, it looks like they're a monoid - sage: [1,2,3]+[] [1, 2, 3]
Asked: 13 years ago
Seen: 4,645 times
Last updated: Feb 03 '12
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