HTTP, URLs, and the query string (?…)

Beginner Data Science Praktikum

Created by Pavel · 21.03.2026 at 01:05 UTC · 1 completed

When you paste a link into the browser or call an API from Python, you are speaking HTTP: the client asks, the server answers with a status and a body. The address in the bar is a URL shaped like scheme://host/path?query#fragment.

The story often hinges on the part after ?: the query string, a chain of key=value pairs joined by &. In one thread you are building a forecast URL—the server needs latitude and longitude to know which place to model. In another thread the same syntax carries utm_source and utm_campaign; the page still loads, because many servers ignore keys they do not use, while analytics tools use those tags to trace where traffic came from.

Building URLs by hand is how you accidentally break spaces and & inside values; urllib.parse.urlencode and requests’ params keep the encoding honest. Same syntax, two roles—API contract versus marketing breadcrumb—and telling them apart is part of reading the web like an engineer.

Background: [1], Python urllib walkthrough [2].

Sources

University approvals: 0

Tasks

Question 1

In https://api.example.com/v1/forecast?latitude=47.3&longitude=8.5, what is the primary role of latitude and longitude in the query string?

Hint

Think about what the server needs to compute a location-specific response.

They are HTML form labels only

They are request parameters consumed by the API to build the response

They always indicate a phishing attempt

They are required by the HTTP protocol for every GET request

Question 2

A landing page URL contains ?utm_source=newsletter&utm_campaign=spring. What is the typical purpose of utm_* parameters?

Hint

UTM is widely used in digital marketing dashboards.

They configure database indexes on the server

They authenticate the user to the API

They support marketing analytics and campaign attribution

They set the page's character encoding

Question 3

Implement count_utm_keys(url: str) -> int counting distinct query parameter names whose lowercase form starts with utm_. Use urllib.parse.urlparse and parse_qs.

Example: https://shop.example/p?utm_source=x&utm_medium=y&id=1 → 2.

Submit the function; expression mode tests call it.

Hint

parse_qs returns a dict mapping each name to a list of values.

from urllib.parse import urlparse, parse_qs


def count_utm_keys(url: str) -> int:
    # TODO: parse query keys and count distinct UTM-prefixed names.
    pass

Starter code is prefilled; replace TODO blocks with your solution.

Runtime output (stdout/stderr)

2 test cases will be used for grading

Run checks runtime behavior only. Final correctness is evaluated when you submit.

Card Info

Topic: Data Science Praktikum
Difficulty: Beginner
Completed: 1 users

Creator

Pavel