Flatten numpy array but also keep index of value positions?

Question

I have several 2D numpy arrays (matrix) and for each one I would like to convert it to vector containing the values of the array and a vector containing each row/column index.

Answer 1

Another way:

arr = np.array([[3, 1, 4],
                [1, 5, 9],
                [2, 6, 5]])

# build out rows array
x = np.arange(arr.shape[0]).reshape(arr.shape[0],1).repeat(arr.shape[1],axis=1)
# build out columns array
y = np.arange(arr.shape[1]).reshape(1,arr.shape[0]).repeat(arr.shape[0],axis=0)

# combine into table
table = np.vstack((arr.reshape(arr.size),x.reshape(arr.size),y.reshape(arr.size))).T
print(table)