group list into a list of lists of given size

''' list_grouping101.py
group a single list into a list of lists of given size
'''

# using a while loop ...
mylist = [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18]
n = 0
size = 3  # desired size of sublist
newlist = []
while n < len(mylist):
    sublist = mylist[n : n + size]
    newlist.append(sublist)
    n += size

print(newlist)

print('-'*60)

# using list comprehension ...
mylist = [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18]
size = 3
newlist = [mylist[n : n + size] for n in range(0, len(mylist), size)]
print(newlist)

''' result ...
[[0, 1, 2], [3, 4, 5], [6, 7, 8], [9, 10, 11], [12, 13, 14], [15, 16, 17], [18]]
------------------------------------------------------------
[[0, 1, 2], [3, 4, 5], [6, 7, 8], [9, 10, 11], [12, 13, 14], [15, 16, 17], [18]]
'''
print('-'*60)

import pprint
mylist = [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]
size = 3
newlist2 = [mylist[n : n + 3] for n in range(0, len(mylist)) if n < len(mylist)-size]
pprint.pprint(newlist2)

'''
[[0, 1, 2],
 [1, 2, 3],
 [2, 3, 4],
 [3, 4, 5],
 [4, 5, 6],
 [5, 6, 7],
 [6, 7, 8],
 [7, 8, 9],
 [8, 9, 10],
 [9, 10, 11],
 [10, 11, 12],
 [11, 12, 13],
 [12, 13, 14],
 [13, 14, 15],
 [14, 15, 16],
 [15, 16, 17],
 [16, 17, 18],
 [17, 18, 19]]

'''