python中列表的常见操作

if not a:
  print "List is empty"

ints = [8, 23, 45, 12, 78]
for idx, val in enumerate(ints):
    print idx, val
0 8
1 23
2 45
3 12
4 78

l=[[1,2,3],[4,5,6], [7], [8,9]]
print([item for sublist in l for item in sublist])
[1, 2, 3, 4, 5, 6, 7, 8, 9]

l=[[1,2,3],[4,5,6], [7], [8,9]]

print(sum(l, []))
[1, 2, 3, 4, 5, 6, 7, 8, 9]

from functools import reduce
l=[[1,2,3],[4,5,6], [7], [8,9]]

print(reduce(lambda x,y: x+y,l))
[1, 2, 3, 4, 5, 6, 7, 8, 9]

list_to_be_sorted = [{'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}]
from operator import itemgetter
newlist = sorted(list_to_be_sorted, key=itemgetter('name'))
print(newlist)

tuple(l[i:i+n] for i in xrange(0, len(l), n))

def chunks(l, n):
    """ Yield successive n-sized chunks from l.
    """
    for i in xrange(0, len(l), n):
        yield l[i:i+n]

mergedlist = listone + listtwo

foo = ['a', 'b', 'c', 'd', 'e']
print(random.choice(foo))

a[start:end:step] # 按照step步长直到end-1结束,并不是从start一个个遍历到end

x = [1, 2, 3]
x.append([4, 5])
print (x)
输出:[1, 2, 3, [4, 5]]

x = [1, 2, 3]
x.extend([4, 5])
print (x)
输出:[1, 2, 3, 4, 5]