converting list of zero length to a matrix of 3*3

[vp1989]

I have a list (length of a list is one) [[1,2,3],[4,5,6]], I like to convert it to a matrix (2*3). something like this [1 2 3 
      4 5 6]

This is an example of a real problem, therefore not putting my large code here. Thanks

[jefsummers]

The example is a list of 2, with each element having 3. That said, you want to flatten the list to be 1 by 6.

mylist = [[1,2,3],[4,5,6]]
flatlist = [item for sublist in mylist for item in sublist]
print(flatlist)

Output:
[1, 2, 3, 4, 5, 6]

[deanhystad]

There is no such thing as a Python matrix. You can have a list of lists, like you show in your example. If you are using numpy you can have an array of arrays.

m = np.array([[1, 2, 3], [4, 5, 6]))

m can have matrix like things done to it like m.transpose() or m.dot(anotherM)

There used to be a matrix class in numpy, but I think it is depreciated.