September 27

Tuples

Tuple is sequence of values separated with comma and enclosed in parentheses.Tuple is very similar to List like accessing values,negative indices and slicing work same as list.
Difference between Tuples and lists are, you can not modify tuples unlike lists that why tuple is immutable object and tuples enclosed with parentheses whereas lists use square brackets.

>>> tup1 = ('python', 'name', 1.2, 20) # Declaring

>>> tup2 = (10, 20, 30, 40); # Declaring

>>> print "tup1[0]: ", tup1[0] #accessing

tup1[0]: python

>>> print "tup2[1:3]: ", tup2[1:3] #slicing

tup2[1:3]: (20, 30)

>>> tup1[1] = "second name" # You cannot update/change tuple elements

Traceback (most recent call last):

File "<pyshell#8>", line 1, in <module>

tup1[1] = "second name"

TypeError: 'tuple' object does not support item assignment

>>>

>>> dir(tup1) # method present in tuples

['__add__', '__class__', '__contains__', '__delattr__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getnewargs__', '__getslice__', '__gt__', '__hash__', '__init__', '__iter__', '__le__', '__len__', '__lt__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__rmul__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'count', 'index']

>>>

Key features of Tuple:

You modify or add element to a tuple

You cannot remove element from a tuple

Tuples are faster than lists, so if you need to define constant set of values use tuples.

Tuples are immutable.You can use tuples as key of dictionary but cannot use list as key

tuple assignment is more elegant

>>> a, b = 1, 2

>>> print "a = %s; b = %s"%(a,b)

a = 1; b = 2

>>> a,b = b,a

>>> print "a = %s; b = %s"%(a,b)

a = 2; b = 1

>>>

You have to add comma for single value tuple

>>> tup1 = (50,);

>>> tup = (50);

>>> print type(tup1)

>>> print type(tup2)

>>>