11/4/13

Tuples



In [2]:

    
t = (1,2)
type(t)









    Out[2]:





tuple



In [4]:

    
t = tuple()
type(t)









    Out[4]:





tuple



In [5]:

    
t = tuple('test')
print t









    



('t', 'e', 's', 't')



In [6]:

    
l = list()
l.append(5)
l.append(6)
t = tuple(l)
print t









    



(5, 6)



In [7]:

    
t = tuple( range(10) )
print t









    



(0, 1, 2, 3, 4, 5, 6, 7, 8, 9)



In [8]:

    
print (5)
print (5,)









    



5
(5,)



In [9]:

    
print (5+3)
print (5+3,)









    



8
(8,)



In [10]:

    
print type( (5) )
print type( (5,) )









    



<type 'int'>
<type 'tuple'>



In [11]:

    
print [5]
print [5,]









    



[5]
[5]

Tuple assignment

Assign multiple values to multiple variables at once



In [12]:

    
print range(2)









    



[0, 1]



In [13]:

    
a, b = range(2)
print a
print b

0
1



In [14]:

    
a,b,c = range(2)









    



---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-14-ad09d1e96dc0> in <module>()
----> 1 a,b,c = range(2)

ValueError: need more than 2 values to unpack



In [15]:

    
d = {1:2,2:3,3:4}
print d.keys()
print d.values()
print d.items()









    



[1, 2, 3]
[2, 3, 4]
[(1, 2), (2, 3), (3, 4)]



In [17]:

    
for key in d:
    print key



In [18]:

    
for value in d.values():
    print value



In [20]:

    
for items in d.items():
    print items









    



(1, 2)
(2, 3)
(3, 4)



In [22]:

    
for key, value in d.items():
    print "key:", key
    print "value:", value









    



key: 1
value: 2
key: 2
value: 3
key: 3
value: 4

multiple return values



In [23]:

    
div = 7 / 3
rem = 7 % 3
print "div:",div
print "rem:",rem









    



div: 2
rem: 1



In [24]:

    
div, rem = divmod(7,3)
print "div:",div
print "rem:",rem









    



div: 2
rem: 1

multiple arguments



In [26]:

    
def addall(*nums):
    total = 0
    for n in nums:
        total = total + n
    return total
print addall(1,2,3,5)



In [30]:

    
t = (7,3)
print divmod(*t)









    



(2, 1)

zip builtin

combines multiple sequences into a list of tuples



In [31]:

    
word = "frog"
nums = [1,2,3,4]
print zip(word,nums)









    



[('f', 1), ('r', 2), ('o', 3), ('g', 4)]

creating dictionaries with tuples



In [32]:

    
d = dict( zip(word,nums) )
print d









    



{'r': 2, 'g': 4, 'o': 3, 'f': 1}

updating/expanding dictionaries



In [36]:

    
d.update( [ ('b',2), ('f', 4) ] )
print d









    



{'a': 4, 'b': 2, 'e': 3, 'g': 4, 'f': 4, 'o': 3, 'r': 2}

tuple assignment in for loops



In [34]:

    
l = [1,2,3,4,5]
for i in range( len(l) ):
    print i, l[i]

print ""

for i,val in enumerate(l):
    print i,val



In [33]: