t2=("A","B","Hello")
alist=["Barney",["Wilma"]]
alist.append(t2)
print(alist.pop(1).extend(t2))
print(alist)
print((alist[1][2].upper()))
print(alist)
Hi guys. I just had a qs regarding tuples as I am new to python.
why does print(alist.pop(1).extend(t2)) give NONE on execution?
Why does print(a list) below that give ['Barney', ('A', 'B', 'Hello')] and not open tuple inside list as the function used is extend and not append?
alist=["Hello"]
t1=(1,2,[3,4],5,6)
t1[2].append(alist)
print(t1)
t1[2].pop().append(t1)
print(a list)
qs- Why does print(a list) in the end print ['Hello', (1, 2, [3, 4], 5, 6)]? is it because the thing that is pooled in the previous sentence i.e. Hello is alist?
list.extend extends the list in place (see the docs: http://docs.python.org/2/tutorial/datastructures.html) , and thus returns none. Rather than having a new variable with the extended list, your list with the new items is still called alist
alist prints ['Barney', ('A', 'B', 'Hello')], because that's what you've asked it to do.
Step by step,
t2=("A","B","Hello")
alist=["Barney",["Wilma"]]
alist.append(t2) # ['Barney', ['Wilma'], ('A', 'B', 'Hello')]
pop1 = alist.pop(1) # ['Wilma']
extend1 = pop1.extend(t2) #extend1 = None, pop1 = ['Wilma', 'A', 'B', 'Hello']
print(alist.pop(1).extend(t2)) # None
print(alist) #you've popped wilma, so the rest remains: ['Barney', ('A', 'B', 'Hello')]
As for third, this should be exactly the behavior you expect. First, you pop hello from alist, then you append all of t1 to the thing you just popped, namely hello. So, ['Hello', (1, 2, [3, 4], 5, 6)] should be what you expected to get. Did you expect something different?
print(alist) on the last line prints ['Hello', (1, 2, [3, 4], 5, 6)], because when you run t1[2].pop(), what you get is a a reference to alist in particular, not an arbitrary list element. So then, the append(t1) appends t1 to the actual alist, which you then print.