索引中的Python列表循环

Question

I have a list of dic

MyList=[
    {'Buy': 'Yes', 'date': monday, 'item': '1234'},
    {'Buy': 'Yes', 'date': monday, 'item': '4'},
    {'Buy': 'Yes', 'date': sunday, 'item': '134'},
    {'Buy': 'Yes', 'date': sunday, 'item': '124'},
    {'Buy': 'Yes', 'date': friday, 'item': '14'},
    {'Buy': 'Yes', 'date': friday, 'item': '234'}
]

I use a loop

for data in Mylist:

so it will go through all the items

if I want to do the same but I want to choose the begin and the end of le loop for example a loop start from 0 to 3 or a loop from 2 to end how can I do that?

thanks in advance

Answer 1

Use slicing:

for data in Mylist[:3]:

or:

for data in Mylist[2:]:

---

Related: Python's slice notation

Answer 2

To loop through the first n elements:

for i in itertools.islice(L, 0, n):
    # do stuff

To loop through the last n elements:

for i in itertools.islice(L, len(L)-n, len(L)):
    # do stuff

To loop through the first n and the last m elements:

for i in itertools.chain(itertools.islice(L, len(L)-n, len(L)), itertools.islice(L, len(L)-m, len(L))):
    # do stuff

Answer 3

If you were interested in printing items 0 through 3, for example, you could do something like this:

for item in MyList[:3]:
    print item