Support
Please support this website. Visit the Amazon using this affiliate link. There won't be any difference in your purchage, we will get some commission for every purchase you make.
Advertise with us
python-tips   0   13866
Difference between list, set and tuples in Python and more such comparisons

In this article we will see key differences between commonly used terms in python. For example difference between tuple and list, difference between range and xrange and so on.


List and Tuples:


List:
- are mutable i.e. we can add, extend or update a list.
- generally are homogeneous data structures.


>>> [x for x in range(10)]
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]


Tuples:
- are immutable i.e. we can not update a tuple.
- generally are heterogeneous data structure.
- is a sequence where position have semantic value.
- are more like records, collection of fixed number of fields.

>>> import time
>>> time.localtime()
time.struct_time(tm_year=2017, tm_mon=9, tm_mday=25, tm_hour=21, tm_min=52, tm_sec=24, tm_wday=0, tm_yday=268, tm_isdst=0)
 

Set:

- is just like mathematical set.
- is unordered.
- is mutable.
- doesn't contain duplicate values.

rana@Brahma: ~$ python3
Python 3.5.2 (default, Nov 23 2017, 16:37:01) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> mylist = [1,2,5,2,3]
>>> a = set(mylist)
>>> a
{1, 2, 3, 5}



range() and xrange():


range():
- In python2 range() function returns a list of integers.

rana@Brahma: ~$ python2
Python 2.7.12 (default, Nov 19 2016, 06:48:10) 
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> range(10)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

 - In python3 range() do whatever xrange use to do in python2 i.e. returns the generator object that can be used to display numbers only by looping. Only particular range is displayed on demand and hence called "lazy evaluation".

rana@Brahma: ~$ python2
Python 2.7.12 (default, Nov 19 2016, 06:48:10) 
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> a = xrange(10)
>>> a
xrange(10)
>>> [i for i in xrange(10)]
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

xrange():
- There is no xrange() function in python3. We already know what xrange() use to do in python2.

>>> a = xrange(10)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'xrange' is not defined

 - Since we are moving towards python3, we will not have any further discussion about it. If you are really interested visit this link.


raw_input() and input():


input():
- In python2, input() tries to run the user input as a valid python expression.

rana@Brahma: ~$ python2
Python 2.7.12 (default, Nov 19 2016, 06:48:10) 
[GCC 5.4.0 20160609] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> input()
2^3
1
>>> input(2**3)
8

 - In python3, return the user input as string.


raw_input():
- In python2, return the user input as string.
- Doesn't exists in python3. To simulate the raw_input() in python3, use eval(input()).



Shallow and deep copy:


Before comparing shallow and deep copy, we must know that normal assignment is just pointing new variable to existing object.

rana@Brahma: ~$ python3
Python 3.6.1 |Anaconda 4.4.0 (64-bit)| (default, May 11 2017, 13:09:58) 
[GCC 4.4.7 20120313 (Red Hat 4.4.7-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> a = [1,2]
>>> b = a
>>> print(id(a) == id(b))
True


Comparison of shallow copy and deep copy is relevant for compound objects i.e. where objects contains another objects.


Shallow copy: Shallow copy creates a new object and then use the reference to refer the inner objects.

>>> a = [[1,2],[3,4]]
>>> b = a.copy()
>>> print(id(a) == id(b))
False
>>> print(id(a[0]) == id(b[0]))
True


Deep copy: deep copy create a new object and recursively copy the inner objects too.

>>> from copy import deepcopy
>>> a = [[1,2],[3,4]]
>>> b = deepcopy(a)
>>> print(id(a) == id(b))
False
>>> print(id(a[0]) == id(b[0]))
False

id() function return the identity of the location of the object in memory.

>>> print(id(a))
139724773442120


Unicode and str:

Here is a nicely written article explaining the difference between str, unicode and byte.

unicode str byte
Python 2 unicode characters raw 8 bit values n/a
Python 3 n/a unicode characters raw 8 bit values


*args and **kwargs:

*args:
- is used to pass the variable length list of non-keyworded arguments to function.

*kwargs:
- is used to pass the variable length list of keyworded arguments to a function.

Always pass arguments in this order : formal arguments then non-keyworded argument list and then keyworded arguments list.    



python-tips   0   13866
0 comments on 'Difference Between List, Set And Tuples In Python And More Such Comparisons'
Login to comment


Related Articles:
Python easter egg - import this and the joke
Zen of python, import this, the hidden easter egg with the joke, source code of Zen of python disobey itself...
Improving python code performance by using lru_cache decorator
Store the result of repetitive python function calls in the cache, Improve python code performance by using lru_cache decorator, caching results of python function, memoization in python...
Solving Python Error- KeyError: 'key_name'
Solving KeyError in python, How to handle KeyError in python dictionary, Safely accessing and deleting keys from python dictionary, try except Key error in Python...
Print statement in Python vs other programming languages
print statement in Python vs Other programming languages, comparing python simplicity with other programming languages, how to print a string in python, print statement in python, comparing python with other languages, python vs java, python vs c++...
DigitalOcean Referral Badge

© 2022-2023 Python Circle   Contact   Sponsor   Archive   Sitemap