#lists

Python Easy Theory

Sign in to star

List operations, methods, slicing, and negative indexing

Lists are mutable ordered sequences that support indexing, slicing, appending, extending, and in-place updates.

• Negative indices count from the end
• Slicing returns a new list
• append and extend do different things

#collections #lists #python

List operations, methods, slicing, and negative indexing

Reveal full answer

Python Medium Theory

Sign in to star

Nested lists and list copy behavior

Nested lists make shallow copies especially important because the outer list may copy while inner lists still alias the same objects.

• Nested structures magnify aliasing bugs
• list() or slicing makes a shallow copy
• deepcopy is for fully independent nested state

#copying #lists #python

Nested lists and list copy behavior

Reveal full answer

React Easy Theory

Sign in to star

Lists and keys in React

React uses keys to identify list items across renders so reconciliation can preserve identity correctly.

• Keys must be stable and unique within the list
• Indexes can break identity when order changes
• Keys affect correctness as well as performance

#keys #lists #react

Lists and keys in React

Reveal full answer

Pandas Easy Theory

Sign in to star

What does explode do in pandas?

`explode` turns each item in a list-like cell into its own row while repeating the other column values.

• List-like values become multiple rows
• Other columns repeat
• Useful before groupby or joins

#lists #pandas #reshaping

What does explode do in pandas?

Reveal full answer