Jaysinh’s own heed

Analyzing the behaviour of Python function slice

2018-09-29T04:47:46+00:00

Last Friday, I was sitting in one of the good coffee shops in Bangalore with my friend. Coffee and discussion is the best combination to release stress. It was looking like a perfect Friday evening until my friend was struck by an idea of asking me a question.

“Let me conduct a quiz.” he said, interrupting our conversation.

“A quiz? Quiz on what?”, I asked.

“On programming”, he said

“What is the level of difficulty then?” I said.

Asking the level of difficulty is important. I never invest my efforts in solving something easy. If he had said easy, I would have ignored to answer, but he said “It is a bit difficult, but not that difficult. I gave a wrong answer to this question in my last interview.”

There was no reason to go back from here. Taking some deep breaths I said, “Please go ahead.”

He stood up, took a tissue paper from a nearby counter and scratched below code on it. ¹ And he asked me by pointing towards that code, “What will be the output of this code?”

def my_function(): l = [0, 1, 2] print(l[30:]) my_function() 

Now it was my turn to give the answer. I looked at the code and tried parsing it in my head — line by line. In my mind, I observed the first line. It was defining a function which seems to be correct. I moved my eyes to the next line. It was defining a variable l of type list and assigning values ranging from 0 to 2. Even this wasn’t looking problematic. So I forwarded to the next line where it was trying to print that variable l by slicing it from starting value 30 to the infinity.

“Well, the start value is 30 which is greater than the length of the list. This should raise an IndexError” I said in my mind. I was about to speak an answer, but suddenly Devil of me flashed.

“It is less than a banana job my dear,” the Devil said to me, “You should take a little advantage of this opportunity my boy.”

Because things were looking in my control, I shook my hands with the Devil.

I said to my friend, “How about betting for some real values?”

Going closer I spoke, “If I answer correctly, You will pay the bill and If I am wrong, This will be a treat from my side.”

He thought for a while and nodded. Now it was my turn to unveil the cards.

I said in a strong voice, “It will raise an IndexError.” And shifted my focus towards the chocolate.

He starred my face for a second and spoke, “Okay. Are you sure about this?”.

This was the hint he gave. I should have taken another shot here. What happens next become a lesson for me.

I said with a flat face, “Yes I am.”

With my answer, he instantly opened his backpack, took his Laptop out and typed the code which he wrote on that tissue.

When I stopped hearing a sound of typing I yelled, “So did I win?”

He turned his laptop towards me and exclaimed, “Not at all!”

When I focused on the screen, the interpreter was printing []. Damn! I lost the bet. Why the hell slice is returning an empty list even when we are trying to slice it with a value which is greater than the length of it! It was surely looking unpythonic behavior. I paid whatever the bill amount was. Entire evening this question was all roaming my mind. After coming home, I decided to justify reasons for returning an empty list instead of raising an IndexError from a slice.

Below are a few reasons justifying such behavior of slice function. I am sharing this with you so that you don’t lose a bet with your friend :) For those who haven’t used slice anytime in their life, I advise to read this tutorial. Reading this guide for understanding how a slice function converts the input values. Especially rule number 3 and 4 referenced there.

Reason number one:

Python lists are more commonly used in iterations. Consider below example:
```
numbers = [0, 1, 2, 3] for number in numbers[30:]: print(number) 
```
If slice was raising an IndexError, then the above code would have to written like this

written like like this
```
numbers = [0, 1, 2, 3] try: for number in numbers[30:]: print(numbers) except IndexError: pass 
```
Or in another way below is also looking reasonable
```
numbers = [0, 1, 2, 3] start = 30 if start < len(numbers): for number in numbers[start:]: print(number) 
```
Both the approaches are looking little lengthy by an obvious reason. And that reason is to prevent executing loop if there are no elements in it. When we observe the behavior of slice called at for in, it makes sense to return an empty list instead of raising an IndexError.

I am not able to find further reasons to return an empty list instead of raising the IndexError. But I am sure, there will be. If you know any other potential reasons for such behavior of slice, please drop me a mail at jaysinhp at gmail dot com or contact me over Twitter @jaysinhp. I will update the reasons at this post and give credits to you. Thanks for reading this post.

Proofreaders: Geoffrey Sneddon, Elijah, Mahendra Yadav, Dhavan Vaidya,

I am using the word “Scratch” because that tissue paper was such a thin that writing by a ballpen torn it. ↩

My experience of mentoring at Django Girls Bangalore 2017

2017-11-14T02:31:25+00:00

TL;DR

Last Sunday, Django Girls Bangalore organized a hands-on session of web programming. This is a small event report from my side.

Detailed overview

Django Girls is not for a profit initiative led by Ola Sitarska and Ola Sendecka. Such movement helps women to learn the skills of website development using the well-known web-framework Django. This community is backed by organizers from many countries. Organizations like The Python Software Foundation, Github, DjangoProject and many more are funding Django Girls.

Django Girls Bangalore chapter was organized by Sourav Singh and Kumar Anirudha. This was my second time mentoring for the Django Girls event. First was for the Ahmedabad chapter. The venue was sponsored by HackerEarth. 8 male and 2 female mentored 21 women during this event. Each mentor was assigned more or less 3 participants. Introducing participants with web development becomes easy with the help of Django Girls handbook. The Django Girls handbook is a combination of beginner-friendly hands-on tutorials described in a simple language. The handbook contains tutorials on basics of Python programming language to deploying your web application. Pupils under me were already ready by pre-configuring Python with their workstation. We started by introducing our selves. We took some time browsing the website of undersea cables. One of the amusing questions I got is, “Isn’t the world connected with Satellites?”. My team was comfortable with the Python, so we quickly skimmed to the part where I introduced them to the basics of web and then Django. I noticed mentors were progressing according to the convenience of participants. Nice amount of time was invested in discussing raised queries. During illumination, we heard a loud call for the lunch. A decent meal was served to all the members. I networked with other mentors and participants during the break. Post-lunch we created a blog app and configured it with our existing project. Overview of Django models topped with the concept of ORM became the arduous task to explain. With the time as a constraint, I focused on admin panel and taught girls about deploying their websites to PythonAnywhere. I am happy with the hard work done by my team. They were able to demonstrate what they did to the world. I was more joyful than them for such achievement.

The closing ceremony turned amusing event for us. 10 copies of Two scoops of Django book were distributed to the participants chosen by random draw strategy. I solemnly thank the authors of the book and Pothi.com for gifting such a nice reference. Participants shared their experiences of the day. Mentors pinpointed helpful resources to look after. They insisted girls would not stop at this point and open their wings by developing websites using skills they learned. T-shirts, stickers and badges were distributed as event swags.

You can find the list of all Django Girls chapters here. Djangonauts are encouraged to become a mentor for Django Girls events in your town. If you can’t finding any in your town, I encourage you to take the responsibility and organize one for your town. If you are already a part of Django Girls community, Why are you not sharing your experience with others?

Proofreaders: Kushal Das, Dhavan Vaidya, Isaul Vargas

PyDelhi Conf 2017: A beautiful conference happened in New Delhi, India

2017-07-21T12:44:03+00:00

TL;DR

PyDelhi conf 2017 was a two-day conference which featured workshops, dev sprints, both full-length and lightning talks. There were workshop sessions without any extra charges. Delhiites should not miss the chance to attend this conference in future. I conducted a workshop titled “Tango with Django” helping beginners to understand the Django web framework.

Detailed Review

About the PyDelhi community

PyDelhi conf 2017 volunteers

The PyDelhi community was known as NCR Python Users Group before few years. This community is performing a role of an umbrella organization for other FLOSS communities across New Delhi, India. They are actively arranging monthly meetups on interesting topics. Last PyCon India which is a national level conference of Python programming language was impressively organized by this community. This year too they took the responsibility of managing it. I am very thankful to this community for their immense contribution to this society. If you are around New Delhi, India then you should not miss the chance to attend their meetups. This community has great people who are always happy to mentor.

PyDelhi conf 2017

Conference T-shirt

PyDelhi conf is a regional level conference of Python programming language organized by PyDelhi community. It is their second year organizing this conference. Last year it was located at JNU University. This year it happened at IIM, Lucknow campus based in Noida, New Delhi, India. I enjoyed various talks which I will mention later here, a workshops section because I was conducting one and some panel discussions because people involved were having a good level of experience. 80% of the time slot was divided equally between 30 minutes talk and 2-hour workshop section. 10% were given to panel discussions and 10% was reserved for lightning talks. The dev sprints were happening in parallel with the conference. The early slot was given to workshops for both the days. One large conference hall was located on a 2nd floor of the building and two halls at the ground floor. Food and beverages were served on the base floor.

Panel Discussion

Registration desk

Tea break

Keynote speakers

Mr. Ricardo Rocha: Mr. Rocha is a software engineer at CERN. I got some time to talk with him post-conference. We discussed his responsibilities at CERN. I was impressed when he explained how he is managing infrastructure with his team. On inquiring opportunities available at CERN he mentioned that the organization is always looking for the talented developers. New grads can keep an eye on various Summer Internship Programs which are very similar to Google Summer of Code program.

Mr. Chris Stucchio: Mr. Stucchio is director of Data Science at Wingify/ VWO. I found him physically fit compared to other software developers (mostly of India). I didn’t get much time to have a word with him.

Interesting Talks

Because I took the wrong metro train, I was late for the inaugural ceremony. I also missed a keynote given by Mr. Rocha. Below talks were impressively presented at the conference.

Let’s talk about GIL by Mr. Amit Kumar: Mr. Kumar discussed various ways to trace threads first and then moved the track towards Global Interpreter Lock. He described why the GIL is important in CPython.
Concurrency in Python 3.0 world - Oh my! by Mr. Anand Pillai: Mr. Pillai is well experienced in programming using Python language. I like getting his advices on various programming topics. He explained how async IO can be leveraged to boost your programs. I got few correct references on understanding latest API of the async library.
Property based testing 101 by Aniket Maithani: I always enjoy chit chatting with Mr. Maithani during conferences. He has jolly nature and always prepared with one liner. He discussed various strategies for generating demo data for test cases. I was amazed by his references, tips and tricks for generating test data.

I love discussing with people rather than sit in on sessions. With that ace-reason, I always lose some important talks presented at the conference. I do not forget to watch them once they are publicly available. This year I missed following talks.

Volunteer Party

I got a warm invitation by the organizers to join the volunteer party, but I was little tensed about my session happening on the next day. So, I decided to go home and improve the slides. I heard from friends that the party was awesome!

My workshop session

Me conducting workshop

I conducted a workshop on Django web framework. “Tango with Django” was chosen as a title with a thought of attracting beginners. I believe this title is already a name of famous book solving the same purpose.

Dev sprints

Me hacking at dev sprints section

The dev sprints were happening parallel with the conference. Mr. Pillai was representing Junction. I decided to test few issues of CPython but didn’t do much. There were a bunch of people hacking but didn’t find anything interesting. The quality of chairs was so an impressive that I have decided to buy the same for my home office.

Why attend this conference?

Free Workshops: The conference has great slot of talks and workshops. Workshops are being conducted by field experts without expecting any other fees. This can be one of the great advantages you leverage from this conference.
Student discounts: If you are a student then you will receive a discount on the conference ticket.
Beginner friendly platform: If you are novice speaker than you will get mentorship from this community. You can conduct a session for beginners.
Networking: You will find senior employees of tech giants, owner of innovative start-ups and professors from well-known universities participating in this conference. It can be a good opportunity for you to network with them.

What was missing?

Lecture hall arrangement: It was difficult to frequently travel to the second floor and come back to the ground floor. I found most people were spending their time on the ground floor rather than attending talks going on upstairs.
No corporate stalls: Despite having corporate sponsors like Microsoft I didn’t find any stall of any company.
The venue for dev sprints: The rooms were designed for teleconference containing circularly arranged wooden tables. This was not creating a collaborative environment. Involved projects were not frequently promoted during the conference.

Thank you PyDelhi community!

I would like to thank all the known, unknown volunteers who performed their best in arranging this conference. I am encouraging PyDelhi community for keep organizing such an affable conference.

Proofreaders: Mr. Daniel Foerster, Mr. Dhavan Vaidya, Mr. Sayan Chowdhury, Mr. Trent Buck

Pycon Pune 2017: A wonderful Python conference

2017-03-14T12:48:02+00:00

tl;dr

The conference is worth attending if you are a student, programmer or a hobbyist. If you are a swag-hungry then don’t expect much as a swag from this conference. If you are a Devsprint lover, then this conference has the coolest Devsprint. A great number of keynote speakers are invited for this conference.

Detailed Experience

Because I was volunteering for this conference I reached Pune one day earlier than the conference days. The volunteer meeting was happening at Reserved-bit.

Volunteer

Reserved-bit

Reserved-bit is the best hackerspace I have ever come across. It has a large collection of programmable boards. You will find boards like Raspberry Pi, Bana Pi, Dragonboard, Bigalbon, BBC-microbit and the 3D printer. Furthermore, this space has a great collection of books on Compilers and Embedded programming. I managed to found few on open-source too. The owners are great hackers. You will love to interact with hacker Siddhesh Poyarekar. Hacker Nisha Poyarekar is volunteering the PyLadies community at Pune.

Pune to Mumbai

I spent my half day in this space. I got the responsibility of receiving one of the keynote speakers who was landing at Mumbai airport midnight. To be frank, estimation of Google Maps between Pune to Mumbai is wrong. It showed nearly 2 hours but it took almost 4.5 hours to reach Mumbai. It took few more minutes to reach the airport. The road is impressively smooth. You will encounter the beautiful mountains of Lonavla. The task of moving from Pune to Mumbai airport, receive Katie and come back to Pune was completed in almost 13 hours. I left from Pune around 4.30 PM and came back at nearly 5 AM next day early morning.

Illness during conference

Because I did a huge amount of traveling at that night, I was unable to get enough sleep. Such tiredness resulted in an eye infection. I managed to attend the first day of the conference, but I was not in a condition to attend the second day. Treatment from local doctor healed me in two days and then I was able to take part into Devsprint.

Conference

The conference was a total of 4 days where the initial two days were for the talks and the end was assigned for a Devsprint. It didn’t overwhelmed me with many tracks but gave the quality talks presented in a single track. The talks were set from 9 AM to 5 PM which was taken little lightly by the attendees.

I was pretty impressed with the keynote speakers of this conference.

Katie Cunningham

Katie is the O’Reilly author. Her book on Accessibility depicts her area of expertise. She is fun to talk to. She likes to listen about developer communities, writing and most importantly computer games. Her broad vision on product development is amazing. She is an avid reader. I enjoyed listening to her experience of being in India for the very first time.

Honza Kral

Honza is the dude who loves contributing to Django. He is a core contributor of Django too. He hacks on Python drivers at Elastic. I was impressed with his suggestions on a code design problem I was trying to solve from the past few months. His suggestions on code design are worth noticing. He is a vimmer and maintains little vim plugins as a part of his interest.

Stephen J. Turnbull

Stephen professes the Dismal Science of Economics. His knowledge is deep-rooted just like his beard. You will enjoy discussing computer science, books and his experience of programming. He is authoring few books written in the Japanese language. Stephen is Emacsite.

Terri Oda

Terri is a security nerd. She spent most of her time exploring tools at Intel. Terri knows how to hide from the spying of the U.S. Government. She is leading Google Summer of Code section from Python Software Foundation. Terri is PSF community service award winner. If you are a student and want to take part in GSoC choosing PSF as your organization then she is the right person to talk to.

Florian Fuchs

His knowledge on ReST API construction is the best. He is a Falcon nerd too. I enjoyed discussing various authentication mechanisms for ReST API with him. He is a Red Hatter.

Nick Coghlan

Nick listens more than he speaks. I will advise you to not disturb him if he is coding. He enjoys concentrating while coding. Getting his mentorship was a great experience. He has been contributing to Core Python for a decade now. You will enjoy discussing on interesting code compositions with him. He is a Red Hatter.

Praveen Patil

Unfortunately, I didn’t get much time to talk with Praveen during this conference. He is a math teacher who teaches concepts of mathematics using Python programming language. You should feel confident to speak with him on Python in education and mathematics with him.

John Hawley

John is the wittiest person that I know. His lines always end with humor. He hacks mostly on hardware and GNU/Linux. Micro Python and GNU/Linux should be considered as part of his interests.

I am sad to declare that I was unable to attend any keynote speeches because of the illness. Mostly I rested at the hotel or talked with people during the conference days.

Volunteer Party

If you are volunteering for this conference, then you will be invited to a volunteer dinner party. We enjoyed party colored disco lights dancing on the bits of the DJ. Punjabi food was served, and if you were above 25 than you were allowed to take a sip of a beer.

Devsprint

Devsprint happen at the Red Hat Headquarters, Pune. I found the building has tight security. You will find an individual pantry section dedicated to each department. We were instructed to hack at a huge cafeteria section. I myself contributed to Core Python. Nick Coghlan was mentoring for Core Python. I reviewed one PR, found one broken test case and wrote a fix of an existing issue with his help. Honza was leading the development of Django web framework. A team of Anand Chitipothu mentored for Web2py. Farhaan Bukhsh mentored for Pagure. John Hawley encouraged contributing to MicroPython. Terr Oda, Stephen Turnbull and Florian Fuchs mentored for GNU/Mailman.

Why attend this conference?

This conference has the coolest Devsprint. The organizers understand the value of the Devsprint in a conference. I have never observed such an importance of Devsprint at any other Python conference happening in India.
If you are a student, then this is a beginner friendly conference. Don’t be afraid to attend if you are a Python noob. You will receive a student concession for the tickets too.
If you are a developer, coming to this conference will inspire you to grow from your present level. You will meet core contributors, lead programmers, owners of startups and project managers. You will find a huge scope of opportunities to network with people.
The conference is single track event. This decision helped me to not miss the interesting talks. In my previous experience, parallel tracks forced me to choose between talks when I was interested in both, which killed me.
I have never seen such a huge amount of keynote speakers at any conference happening in India. Keynote speakers were the main attraction of this conference.

What was missing?

If you are a swag-hungry fellow than attending this conference won’t be worth it. The conference attendees have to be satisfied with the conference T-shirt.
I observed there were fewer corporate stalls than at other Python conferences. A stole from Reserved-bit, Red Hat and PSF community stall was there.
A workshop section was completely missing. In my opinion, the workshop helps the beginners to start. There were a few topics which can be better represented as workshop rather than a talk.
I was unable to observe any dedicated section for an open space discussion. This section is helpful for communities and contributors to discuss interesting problems and think together.

Jaysinh’s own heed

Analyzing the behaviour of Python function slice

Proofreaders: Geoffrey Sneddon, Elijah, Mahendra Yadav, Dhavan Vaidya,

My experience of mentoring at Django Girls Bangalore 2017

TL;DR

Detailed overview

Proofreaders: Kushal Das, Dhavan Vaidya, Isaul Vargas

PyDelhi Conf 2017: A beautiful conference happened in New Delhi, India

TL;DR

Detailed Review

About the PyDelhi community

Keynote speakers

Interesting Talks

Volunteer Party

My workshop session

Dev sprints

Why attend this conference?

What was missing?

Thank you PyDelhi community!

Proofreaders: Mr. Daniel Foerster, Mr. Dhavan Vaidya, Mr. Sayan Chowdhury, Mr. Trent Buck

Pycon Pune 2017: A wonderful Python conference

tl;dr

Detailed Experience

Volunteer

Reserved-bit

Pune to Mumbai

Illness during conference

Conference

Volunteer Party

Devsprint

Why attend this conference?

What was missing?

Proofreader: Benaiah Mischenko, Chameleon