In [ ]:

    

# Tuples
# Tuples are readonly representation of list like data.
# days of weeks - 7 days - sun,mon,tue,wed,thu,fri,sat


    

In [5]:

    

# how to create a tuple.
days_of_week = ('sun','mon','tue','wed','thu','fri','sat')
print days_of_week,type(days_of_week)

empty_tuple = tuple()
print empty_tuple,type(empty_tuple)

empty_tuple1 = ()
print empty_tuple1,type(empty_tuple1)


    

    




('sun', 'mon', 'tue', 'wed', 'thu', 'fri', 'sat') <type 'tuple'>
() <type 'tuple'>
() <type 'tuple'>

In [9]:

    

# what is tuple?

my_string = "python"
print my_string,type(my_string)

my_string = ("python")
print my_string,type(my_string)

my_string = ("python",)
print my_string,type(my_string)

my_string = "python","perl","shell","linux"
print my_string,type(my_string)


    

    




python <type 'str'>
python <type 'str'>
('python',) <type 'tuple'>
('python', 'perl', 'shell', 'linux') <type 'tuple'>

In [10]:

    

# lists vs tuples vs string

# strings are sequence of characters. you cannot index a comma seperated strings.
# my_string = "python"  # true
# my_string = "python,perl,shell,linux" # true
# my_string = "python","perl","shell","linux"  # False
# you cannot modify the contents of a string.

# List is a sequence of values , which are indexed and are read-write.
# days_of_week = ['sun','mon','tue','wed','thu','fri','sat']
# you can modify the elements of a list.

# Tuple is a sequence of values , which are indexed but are readonly.
# days_of_week = ('sun','mon','tue','wed','thu','fri','sat')
# you cannot modify the elements of a tuple


    

In [11]:

    

my_string ="python"
 my_string[0] = 'T'


    

    




---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-11-32430e616bae> in <module>()
      1 my_string ="python"
----> 2 my_string[0] = 'T'

TypeError: 'str' object does not support item assignment

In [12]:

    

days_of_week = ['sun','mon','tue','wed','thu','fri','sat']
days_of_week[0] = "SUN"
print days_of_week


    

    




['SUN', 'mon', 'tue', 'wed', 'thu', 'fri', 'sat']

In [13]:

    

days_of_week = ('sun','mon','tue','wed','thu','fri','sat')
days_of_week[0] = "SUN"


    

    




---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-13-a86265b9f377> in <module>()
      1 days_of_week = ('sun','mon','tue','wed','thu','fri','sat')
----> 2 days_of_week[0] = "SUN"

TypeError: 'tuple' object does not support item assignment

In [16]:

    

# string - sequence of characters
my_string = "python,perl,shell,linux"
print my_string,type(my_string)
print my_string[0]


    

    




python,perl,shell,linux <type 'str'>
p

In [17]:

    

# tuple - sequence of values
my_string = ("python","perl","shell","linux")
print my_string,type(my_string)
print my_string[0]


    

    




('python', 'perl', 'shell', 'linux') <type 'tuple'>
python

In [26]:

    

# packing and unpacking
# lists and tuples are called packing. () or []

# ("python","perl","shell","linux") -> a packing
# unpacking
a,b,c,d = ("python","perl","shell","linux")
print a,type(a)
print b,type(b)
print c,type(c)
print d,type(d)


    

    




python <type 'str'>
perl <type 'str'>
shell <type 'str'>
linux <type 'str'>

In [19]:

    

# while unpacking .. elements on left hand side should be equal to elements on right hand side.
# LHS = RHS
a,b,c = ("python","perl","shell","linux")


    

    




---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-19-57001ff85a95> in <module>()
      1 # while unpacking .. elements on left hand side should be equal to elements on right hand side.
      2 # LHS = RHS
----> 3 a,b,c = ("python","perl","shell","linux")

ValueError: too many values to unpack

In [20]:

    

a,b,c,d,e = ("python","perl","shell","linux")


    

    




---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-20-182658a2351c> in <module>()
----> 1 a,b,c,d,e = ("python","perl","shell","linux")

ValueError: need more than 4 values to unpack

In [24]:

    

# lists and tuples

my_students = ['vipin','avinash','azhar','kumar']
my_exams    = ['python','django','ruby','ansibel']

# logic
#1) if the student name is part of the my_students list.

name='vipin'
print 'vipin' in my_students
print 'rajni' in my_students

#2) corelate the student id to that of the my_exams
# getting the index of the student from my_students list

print my_students.index('vipin')
print my_exams[my_students.index('vipin')]


    

    




True
False
0
python

In [27]:

    

# name of the student.
name = 'kumar'

if name in my_students:
    print "{} is going to give the exam {}".format(name,my_exams[my_students.index(name)])


    

    




kumar is going to give the exam ansibel

In [28]:

    

# principle - anti-climax
my_students.sort()
print my_students
print my_exams


    

    




['avinash', 'azhar', 'kumar', 'vipin']
['python', 'django', 'ruby', 'ansibel']

In [29]:

    

# name of the student.
name = 'kumar'

if name in my_students:
    print "{} is going to give the exam {}".format(name,my_exams[my_students.index(name)])


    

    




kumar is going to give the exam ruby

In [33]:

    

#my_students = ['vipin','avinash','azhar','kumar']
#my_exams    = ['python','django','ruby','ansibel']
# list of tuples

name = 'azhar'
new_exams = [('vipin','python'),('avinash','django'),('azhar','ruby'),('kumar','ansibel')]

for student,subject in new_exams:
    if student == name:
        print "{} is going to give exam {}".format(student,subject)


    

    




azhar is going to give exam ruby

In [34]:

    

name = 'avinash'

for student,subject in new_exams:
    if student == name:
        print "{} is going to give exam {}".format(student,subject)


    

    




avinash is going to give exam django

In [35]:

    

# anti-climax - sorting
new_exams.sort()
print new_exams


    

    




[('avinash', 'django'), ('azhar', 'ruby'), ('kumar', 'ansibel'), ('vipin', 'python')]

In [36]:

    

name = 'vipin'

for student,subject in new_exams:
    if student == name:
        print "{} is going to give exam {}".format(student,subject)


    

    




vipin is going to give exam python

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# managing the data with right datastructures. 
#


    

In [38]:

    

# tuples

days_of_week = ('sun','mon','tue','wed','thu','fri','sat')
print days_of_week

print dir(days_of_week)


    

    




('sun', 'mon', 'tue', 'wed', 'thu', 'fri', 'sat')
['__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']

In [39]:

    

print days_of_week.count('sun') # 1
print days_of_week.index('wed') # 3


    

    




1
3

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