how to create a list of lists

Question

My Python code generates a list everytime it loops:

list = np.genfromtxt(\'temp.txt\', usecols=3, dtype=[(\'floatname\',\'float\')], skip_header=1)
         


        

Answer 1

Create your list before your loop, else it will be created at each loop.

>>> list1 = []
>>> for i in range(10) :
...   list1.append( range(i,10) )
...
>>> list1
[[0, 1, 2, 3, 4, 5, 6, 7, 8, 9], [1, 2, 3, 4, 5, 6, 7, 8, 9], [2, 3, 4, 5, 6, 7, 8, 9], [3, 4, 5, 6, 7, 8, 9], [4, 5, 6, 7, 8, 9], [5, 6, 7, 8, 9], [6, 7, 8, 9], [7, 8, 9], [8, 9], [9]]