Initializing a list of lists

[tkpmep]

I want to create a list of lists, each of which is identical, but which
can be modified independently i.e:

x = [ [0], [0], [0] ]
x[0].append(1)
x

[[0, 1], [0], [0]]

The above construct works if I have only few items, but if I have many,
I'd prefer to write

N =3
x =N*[[0]]
x

[[0], [0], [0]]

If I now try extending the lists indepently, I cannot, as they all
point to the same list object

x[0].append(1)
x

[[0, 1], [0, 1], [0, 1]]

Is there a simple way to create a list of independent lists?

Thanks in advance

Thomas Philips

 

[ZeD]

Ciao, (e-mail address removed)! Che stavi dicendo?

Is there a simple way to create a list of independent lists?

N=3
x=[[0] for e in range(N)]

 

[Tim Chase]

The above construct works if I have only few items, but if I have many,

I'd prefer to write

N =3
x =N*[[0]]
x

[[0], [0], [0]]

If I now try extending the lists indepently, I cannot, as they all
point to the same list object

x[0].append(1)
x

[[0, 1], [0, 1], [0, 1]]

Is there a simple way to create a list of independent lists?

My first thought would be

>>> N = 10
>>> x = [[0] for _ in range(N)]
>>> x[0].append(1)
>>> x

[[0, 1], [0], [0], [0], [0], [0], [0], [0], [0], [0]]

HTH,

-tkc

 

[Ron Adam]

I want to create a list of lists, each of which is identical, but which
can be modified independently i.e:

x = [ [0], [0], [0] ]
x[0].append(1)
x

[[0, 1], [0], [0]]

The above construct works if I have only few items, but if I have many,
I'd prefer to write

N =3
x =N*[[0]]
x

[[0], [0], [0]]

If I now try extending the lists indepently, I cannot, as they all
point to the same list object

x[0].append(1)
x

[[0, 1], [0, 1], [0, 1]]

Is there a simple way to create a list of independent lists?

Try this...

x, y, value = 3, 3, 0
L = [[value]*x for i in xrange(y)]


Cheers,
Ron