Working with the elements of the "matrix" created by genfromtxt, Python3.4
Question: I import a .txt file with the command `tab = np.genfromtxt()` and it creates a
kind of matrix. I need to work with its contents. When I visualize the
elements with the command

    
    
    for i in range n:
        print(tab[n][:])
    

it works and I can use matrix elements with `[][]` like if the first is the
line number and the second the column one. Instead when I use the command
`tab[0][:]` the command is like I used `tab[:][0]`, i.e. I can visualize only
the line 0 with all its elements (`tab[0][:]=tab[:][0]`). What's the way I can
move in a fixed column number and use all the line elements without a cicle
"for i in range()" type? Thank you.


Answer: All indices of a numpy array should be in a single `[]` separated by commas
(ie `tab[i,j]`), if you provide just one index you get an array with the first
dimension equal to that index (a row in this case). So `tab[:]` returns the
whole matrix again. When you apply `[0]` over `tab[:]` it's the same as
`tab[0]`

For iterating over columns:

    
    
    for i in range n:
        print(tab[:,n])
    

For iterating over rows:

    
    
    for i in range n:
        print(tab[n,:])
    

