Tuples¶
- http://openbookproject.net/thinkcs/python/english3e/tuples.html
- containers used for grouping data values surrounded with parenthesis
- data values in tuples are called elements/items/members
- two major operations done with tuples are:
- packing (creating tuples)
- unpacking (storing data into individual variables)
In [1]:
year_born = ("Paris Hilton", 1981) # tuple packing
In [2]:
print(year_born)
('Paris Hilton', 1981)
In [11]:
star = "Paris", 'J', 'Hilton', 1981, 32, 1.2 # tuple packing
In [12]:
star
Out[12]:
('Paris', 'J', 'Hilton', 1981, 32, 1.2)
In [13]:
type(star)
Out[13]:
tuple
In [14]:
# tuple assignment
fname, mi, lname, year, age, income = star # tuple unpacking;
# no. of variables must match no. tuple values
In [9]:
fname
Out[9]:
'Paris'
In [10]:
lname
Out[10]:
'Hilton'
In [11]:
print(income)
1.2
In [12]:
# swap values of two variables
a = 100
b = 200
a, b = b, a
In [13]:
print(a, b)
200 100
Member access¶
- each member of tuple can be accessed using [ index ] operator
- index is 0 based or starts from 0
In [1]:
name = ('John', 'A.', 'Smith')
In [3]:
print(name[0], name[1], name[2])
John A. Smith
len built-in function¶
- gives the length (no. of elements) of tuple
In [4]:
len(name)
Out[4]:
3
Tuple membership¶
- in and not in boolean operators let's you check for membership
In [7]:
'John' in name
Out[7]:
True
In [8]:
'B.' in name
Out[8]:
False
In [9]:
'Jake' not in name
Out[9]:
True
Tuples can be returned from a function¶
In [29]:
def maxAndMin(a, b, c, d, e):
myMax = a #max(a, b, c, d, e)
if myMax < b:
myMax = b
if myMax < c:
myMax = c
if myMax < d:
myMax = d
if myMax < e:
myMax = e
values = [a, b, c, d, e]
myMin = min(values)
return (myMax, myMin)
In [30]:
ab = maxAndMin(10, 20, 5, 100, 34)
print('max =', ab[0], 'min=', ab[1])
max = 100 min= 5
Tuples are immutable¶
- can't change tuple in-place or update its elements similar to string
In [5]:
a = (1, 2, 3)
print(a[0])
1
In [6]:
a[0] = 100
--------------------------------------------------------------------------- TypeError Traceback (most recent call last) <ipython-input-6-b6d7a4db9a51> in <module>() ----> 1 a[0] = 100 TypeError: 'tuple' object does not support item assignment