# Lists

>>> names = ["dave", "mark", "ann", "phil"]
>>> names.insert(2, "thomas")
>>> print names
['dave', 'mark', 'thomas', 'ann', 'phil']
>>> alist = [[1,2,3], [4,5,6], [7,8,9]]
>>> alist[2]
[7, 8, 9]
>>> alist[2][1]
8
>>> alist[2].insert(1,7.5)
>>> print alist
[[1, 2, 3], [4, 5, 6], [7, 7.5, 8, 9]]

# Iteration

>>> nlist = [2,5,7,18,19,24,220]
>>> mysum = 0
>>> for x in nlist:
...   mysum = mysum + x
...
>>> print mysum
295
>>> mysum = 0
>>> for x in nlist:
...   mysum = mysum + x
...   print "Sum is now", mysum
... 
Sum is now 2
Sum is now 7
Sum is now 14
Sum is now 32
Sum is now 51
Sum is now 75
Sum is now 295
>>> print nlist
[2, 5, 7, 18, 19, 24, 220]
>>> counter = 0
>>> for x in nlist:
...   counter = counter + 1
... 
>>> print counter
7
>>> mysum/counter
42
>>> mysum/float(counter)
42.142857142857146
>>> counter = 0.0
>>> for x in nlist:
...   counter = counter + 1
... 
>>> mysum/counter
42.142857142857146
>>> counter
7.0
>>> sum(nlist)
295
>>> len(nlist)
7
>>> sum(nlist)/float(len(nlist))
42.142857142857146
>>> nlist
[2, 5, 7, 18, 19, 24, 220]
>>> nlist[2]
7
>>> nlist[2:5]
[7, 18, 19]
>>> nlist[2:]
[7, 18, 19, 24, 220]
>>> nlist[:7]
[2, 5, 7, 18, 19, 24, 220]
>>> nlist[0:7]
[2, 5, 7, 18, 19, 24, 220]
>>> nlist[0:4]
[2, 5, 7, 18]
>>> firstfour = nlist[:4]
>>> firstfour.append(5)
>>> print firstfour
[2, 5, 7, 18, 5]
>>> for c in "Mus Musculus":
...   print c.lower()
... 
m
u
s
 
m
u
s
c
u
l
u
s
>>> s = ''
>>> for c in "Mus musculus":
...   s = s + c.lower()
... 
>>> s
'mus musculus'