Files: CSV, JSON, JSON Lines, paths

from pathlib import Path
import csv

data = Path(".")
print(sorted(p.name for p in data.glob("*.csv"))[:4])
p = Path("orders.csv")
print(p.suffix, p.stat().st_size, "bytes")

with open("orders.csv", newline="", encoding="utf-8") as f:
    reader = csv.DictReader(f)
    print(reader.fieldnames)
    rows = [{**r, "amount": float(r["amount"])} for r in reader]

out = Path("delivered.csv")
with out.open("w", newline="", encoding="utf-8") as f:
    w = csv.DictWriter(f, fieldnames=["order_id", "amount"],
                       extrasaction="ignore")
    w.writeheader()
    w.writerows(r for r in rows if r["status"] == "delivered")
print(out.read_text().splitlines()[:3])

['employees.csv', 'logins.csv', 'order_items.csv', 'orders.csv']
.csv 566 bytes
['order_id', 'customer_id', 'order_date', 'status', 'amount']
['order_id,amount', '101,1198.0', '102,796.0']

import json

with open("events.jsonl", encoding="utf-8") as f:
    for i, line in enumerate(f):          # one record at a time
        event = json.loads(line)
        if i < 2:
            print(event["event"], event["props"]["device"])

customers = json.load(open("customers.json"))   # whole file
print(len(customers), customers[1]["address"])
print(json.dumps({"id": 1, "city": None}))

view mobile
cart mobile
8 {'city': 'Mumbai', 'pincode': '400001'}
{"id": 1, "city": null}