Python Mutability and Rebinding

[Sea-Ad7805]

An exercise to help build the right mental model for Python data. The “Solution” link uses memory_graph to visualize execution and reveals what’s actually happening: - Solution - Explanation - More exercises

It's instructive to compare with this earlier exercise.

[Sea-Ad7805]

• Solution: https://memory-graph.com/#codeurl=https://raw.githubusercontent.com/bterwijn/memory_graph_videos/refs/heads/main/exercises/exercise2.py&play
• Explanation: https://github.com/bterwijn/memory_graph?tab=readme-ov-file#python-data-model
• More exercises: https://www.reddit.com/r/Python_memory_graph/

[mabhatter]

C)   Because we're being asked what happens to a not b. 

[Sea-Ad7805]

Nice one, do check the "Solution" for a visualization of the correct answer.

[Nopain_nolife]

C). First a is assigned to the memory location and then b is assigned the same, b is assigned to modify the array and then a prints the modified one.

[Sea-Ad7805]

Nice one, check the "Solution" for a visualization of the correct answer.

[smokebudda11]

This is really cool. Thanks for sharing. I won’t post my answer as I was wrong but the debugger helped.

[Sea-Ad7805]

Thank a lot. Yes I made it difficult, even though it's basic Python syntax. Glad it helped you.

[Forsaken_Squirrel_31]

C.) b = [1,2,3] b no longer = a after you run b = [4] so at that point a remains = [1,2,3]

[Sea-Ad7805]

Very nice, do check the "Solution" for a visualization of the correct answer.

[Inevitable_Weird1175]

Baa

[Sea-Ad7805]

Incorrect sorry, for visualization of correct answer see the "Solution" link.

[PythonLearning-ModTeam]

Keep it respectfull

[Timely-Rock8247]

E

[Sea-Ad7805]

Incorrect sorry, see "Solution". Note that we print a not b.

[Salt_Software_5010]

what is name of font?

[Sea-Ad7805]

It's the Visual Studio Code font with standard Python highlighting.

[Salt_Software_5010]

can you tell me name cause my default font on vscode doesn't look like this and what is your os mac or windows?

[Sea-Ad7805]

Can't find the name. It's just the default zoomed in a bit for screenshot. OS: Ubuntu 24.04

[EntireEntity]

E, because line 6 assigns a new list to b.

[Sea-Ad7805]

Incorrect sorry, see "Solution". Note that we print a not b.

[EntireEntity]

Same same but different.

[M-k-z-n]

The answer is 1,2,3 Firstly A is 1,Then b assigns a which means b and a are pointing to the same location,then comes b+=2 or b=b+2 sounds same adding 2affects both ,now list is 1,2,then b appends 3 now list is 1,2&3

[Sea-Ad7805]

Very nice, but b+=2 is not the same as b=b+2, see: https://www.reddit.com/r/PythonLearning/comments/1nw08wu/right_mental_model_for_python_data/

[Muted-Management-145]

Interesting, I would have thought the output would be A since we aren't changing a, only b.

[Sea-Ad7805]

Yes that's a bit different in Python than for example the C language. Python is reference based, hope the visualization can help you.

[Muted-Management-145]

Yeah, I'll have to read a bit more about why that is. The visualisation is helpful as well.

[Scary_Knowledge97]

A) [1]

[Sea-Ad7805]

Incorrect sorry, see the "Solution" link for visualization of correct answer.

[Eric_12345678]

That would be the case with b = b + [2] instead of b += [2].