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How to Count Words in a String in Python
Split a paragraph on whitespace and return the number of words using Python's built-in string methods.
def count_words(paragraph: str) -> int:
words = paragraph.split()
return len(words)
if __name__ == "__main__":
paragraph = "The quick brown fox jumps over the lazy dog."
result = count_words(paragraph)
print(f"Word count: {result}")Build adjacency dict graph from edges in Python
Convert a list of edges into an undirected adjacency dictionary, mapping each node to its neighbors, with sorted output.
def build_adjacency_dict(edges):
graph = {}
for u, v in edges:
if u not in graph:
graph[u] = []
if v not in graph:
graph[v] = []
graph[u].append(v)
graph[v].append(u)
return graph
if __name__ == "__main__":
edges = [(1, 2), (2, 3), (3, 4), (4, 1)…Graph Class with Adjacency Dict in Python
Build an undirected graph class using a dictionary of adjacency lists with methods to add vertices, edges, remove edges, and query neighbors.
class Graph:
def __init__(self):
self.adjacency = {}
def add_vertex(self, vertex):
if vertex not in self.adjacency:
self.adjacency[vertex] = []
def add_edge(self, u, v):
self.add_vertex(u)
self.add_vertex(v)
self.adjacency[u].append(v)
self.adja…Depth First Search Traversal Order in Python
Recursive depth-first search that returns the visit order of nodes in an adjacency list graph starting from a given node.
def dfs_order(adj, start):
visited = set()
order = []
def dfs(node):
visited.add(node)
order.append(node)
for neighbor in adj.get(node, []):
if neighbor not in visited:
dfs(neighbor)
dfs(start)
return order
if __name__ == "__main__":
# Dem…How to Get the Breadth-First Traversal Order of a Graph in Python
Performs a breadth-first search on an adjacency list and returns the order nodes are visited, using a deque for efficient queue operations.
from collections import deque
def bfs_order(adjacency, start=0):
"""Return the order nodes are visited in a breadth-first traversal."""
visited = set()
order = []
queue = deque([start])
visited.add(start)
while queue:
node = queue.popleft()
order.append(node)
for neig…Build a Command-Line Password Generator in Python
Generate cryptographically strong random passwords using Python's secrets module and print them for command-line use.
import secrets
import string
def generate_password(length=16):
"""Generate a cryptographically strong random password."""
alphabet = string.ascii_letters + string.digits + string.punctuation
password = ''.join(secrets.choice(alphabet) for _ in range(length))
return password
if __name__ == "__main__":…Build a Simple Log Graph in Python
Create a basic one-dimensional bar chart from log lines by counting occurrences of leading numeric keys.
import heapq
def log_graph(log_lines: list[str]) -> str:
"""Build a simple per-line, one-dimensional visual graph from log entries."""
counts: dict[int, int] = {}
for line in log_lines:
tokens = line.split()
if tokens:
try:
idx = int(tokens[0])
exce…How to Mock a GraphQL Query Type in Python
Create a lightweight mock of a GraphQL Query type to simulate repository lookups without a server.
import json
class Query:
def __init__(self):
self.starred_repos = [
{"id": 1, "name": "graphql", "owner": "graphql"}
]
def repository(self, name):
if name == "graphql":
return {"id": 1, "name": "graphql", "stargazerCount": 85000}
return None
if __name…How to Mock a GraphQL Backend in Python
Create an in-memory GraphQL mock backend using dataclasses and resolver methods returning plain dictionaries.
from dataclasses import dataclass, asdict
from typing import Any, Dict, List
@dataclass
class Product:
id: int
name: str
price: float
@dataclass
class User:
id: int
username: str
class MockGraphQLBackend:
def __init__(self) -> None:
self.products = [
Product(id=1, name…Geo shard by region in Python
Maps users to database shards based on geographic region with a deterministic hash fallback.
import json
from collections import defaultdict
REGION_SHARD_MAP = {
"na": ["shard-01", "shard-02"],
"eu": ["shard-03", "shard-04", "shard-05"],
"ap": ["shard-06"],
"sa": ["shard-07", "shard-08"],
}
# user_id -> region (mock lookup)
USER_REGIONS = {
"u_1001": "na",
"u_1002": "eu",
"u_1003…How to Generate PKCE Code Challenge in Python
This Python script generates a PKCE code verifier and its corresponding S256 code challenge for secure OAuth2 authorization flows.
import base64
import hashlib
import os
import secrets
import string
def generate_code_verifier(length=64):
alphabet = string.ascii_letters + string.digits + "-._~"
return "".join(secrets.choice(alphabet) for _ in range(length))
def generate_code_challenge(code_verifier, method="S256"):
if method == "S256…How to Generate and Verify HMAC Signatures in Python
Create and validate HMAC-SHA256 signatures with a shared secret key using Python's hmac and hashlib modules.
import hashlib
import hmac
SECRET_KEY = b"pepper-secret-2024"
def generate_hmac(message: str) -> str:
return hmac.new(SECRET_KEY, message.encode("utf-8"), hashlib.sha256).hexdigest()
def verify_hmac(message: str, received_hmac: str) -> bool:
expected = generate_hmac(message)
return hmac.compare_digest(e…Browse by section
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