Phase 2 — Collections
Phase 2 — Collections
Goals for this phase, and a full JS/TS → Python cheat sheet
Estimated time: ~2 hours.
This is probably the most important Python section for backend development. Almost every API you write will pass data around as lists and dicts.
Goals
By the end of this phase you should be comfortable with:
listtuplesetdict(especially this one)- indexing
- slicing
append,remove,popget,keys,values,itemsin
Each topic is its own page in the sidebar, taught with a JS/TS → Python comparison, followed by a small example.
Cheat sheet
JavaScript / TypeScript Python
──────────────────────────────────────────
Array list
Object dict
Set set
frozen array / tuple-like tuple
arr.push(x) list.append(x)
arr.pop() list.pop()
arr.splice(i, 1) del list[i]
arr.filter(v => v !== x) list.remove(x)
arr[0] list[0]
arr.at(-1) list[-1]
arr.slice(1, 3) list[1:3]
Object.keys(obj) dict.keys()
Object.values(obj) dict.values()
Object.entries(obj) dict.items()
obj.x ?? obj["x"] dict.get("x")
'x' in obj 'x' in dict
arr.includes(x) x in list