Question

I am learning python, now, i came across a code snippet which looks like this:

my_name={'sujit','amit','ajit','arijit'}
for i, names in enumerate(my_name):
    print "%s" %(names[i])

OUTPUT

s
m
i
t

But when I modify the code as:

my_name=['sujit','amit','ajit','arijit']
for i, names in enumerate(my_name):
    print "%s" %(names[i])

OUTPUT

s
m
i
j

What is the difference between {} and []? The [] is giving me the desired result for printing the ith character of the current name from the list. Bu the use of {} is not.

Answer 1

{} creates a set, whereas [] creates a list. The key differences are:

• the list preserves the order, whereas the set does not;
• the list preserves duplicates, whereas the set does not;
• the list can be accessed through indexing (i.e. l[5]), whereas the set can not.

The first point holds the key to your puzzle. When you use a list, the loop iterates over the names in order. When you’re using a set, the loop iterates over the elements in an unspecified order, which in my Python interpreter happens to be sujit, amit, arijit, ajit.

P.S. {} can also be used to create a dictionary: {'a':1, 'b':2, 'c':3}.