Combining two list of lists into one-CodePudding

There are two lists of lists, I need to make one list out of them.

a = [[1,2,3],[4,5,6]]
b = [[1,2,3],[4,5,6]]
I_need = [[1,1,2,2,3,3],[4,4,5,5,6,6]]

or one more question, how to duplicate the list to have the same result. I will be glad for any help!

CodePudding user response：

If you have python lists:

I_need = [[e for x in zip(*l) for e in x] for l in zip(a,b)]

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

If you have numpy arrays:

a = np.array([[1,2,3],[4,5,6]])
b = np.array([[1,2,3],[4,5,6]])
I_need = np.c_[a.ravel(), b.ravel()].reshape(2,-1)

output:

array([[1, 1, 2, 2, 3, 3],
       [4, 4, 5, 5, 6, 6]])

CodePudding user response：

As you marked your question with Numpy tag, I assume that you want to use just Numpy.

To easier tell apart elements of both source arrays, I defined them as:

a = [[ 1, 2, 3],[ 4, 5, 6]]
b = [[10,20,30],[40,50,60]]

To get your expected result, run:

result = np.dstack([a, b]).reshape(2, -1)

The result is:

array([[ 1, 10,  2, 20,  3, 30],
       [ 4, 40,  5, 50,  6, 60]])

If you want a plain pythonic list (instead of a Numpy array), append .tolist() to your code.