Files and Real-World Data

Use Path("journal.txt").write_text(...) or open(..., "w"). Reject empty input before writing; w mode replaces existing content.

One possible implementation. Check the book's tests and try an extension after comparing.

# Challenge 71 - Write a Learning Journal
from pathlib import Path

entry = input("Journal entry: ").strip()
if entry:
    Path("journal.txt").write_text(
        "LEARNING JOURNAL\n" + entry + "\n", encoding="utf-8"
    )
    print("Saved to journal.txt")
else:
    print("Nothing saved: entry was blank.")

Skip the first heading line. Use enumerate(entries, 1) for original entry numbers and compare keyword.casefold() with each entry.casefold().

One possible implementation. Check the book's tests and try an extension after comparing.

# Challenge 72 - Read Your Journal
from pathlib import Path

path = Path("journal.txt")
if not path.exists():
    print("Journal file not found.")
else:
    lines = path.read_text(encoding="utf-8").splitlines()
    entries = [line.strip() for line in lines[1:] if line.strip()]
    keyword = input("Search term: ").strip().casefold()
    matches = [(number, text) for number, text in
               enumerate(entries, 1) if keyword and keyword in text.casefold()]
    if matches:
        for number, text in matches:
            print(f"{number}. {text}")
    else:
        print("No matching entries.")

Choose mode "a" (append), not "w" (replace). A newline after each task makes later reading much easier.

One possible implementation. Check the book's tests and try an extension after comparing.

# Challenge 73 - Add to the To-Do List
from pathlib import Path

task = input("New task: ").strip()
if not task:
    print("Nothing added: task was blank.")
else:
    with Path("tasks.txt").open("a", encoding="utf-8") as file:
        file.write(task + "\n")
    print("Task added.")

The expression bool(line.strip()) is False for a line containing only whitespace.

One possible implementation. Check the book's tests and try an extension after comparing.

# Challenge 74 - Count the Log Entries
from pathlib import Path

path = Path("activity_log.txt")
if not path.exists():
    print("Activity log not found.")
else:
    lines = path.read_text(encoding="utf-8").splitlines()
    count = sum(1 for line in lines if line.strip())
    print(f"Entries: {count}")

Use any(keyword in entry.casefold() for keyword in keywords); append each matching entry only once.

One possible implementation. Check the book's tests and try an extension after comparing.

# Challenge 75 - Find Positive Feedback
from pathlib import Path

keywords = ("helpful", "clear", "friendly")
path = Path("feedback.txt")
if not path.exists():
    print("Feedback file not found.")
else:
    entries = [line.strip() for line in
               path.read_text(encoding="utf-8").splitlines() if line.strip()]
    matches = [entry for entry in entries
               if any(word in entry.casefold() for word in keywords)]
    print(f"Positive entries: {len(matches)}")

Remove delimiter=";". csv.writer uses commas by default. Use newline="" and re-read with csv.reader.

One possible implementation. Check the book's tests and try an extension after comparing.

# Challenge 76 - Create a Scores CSV
import csv

scores = [("Alex", 84), ("Bea", 91), ("Chris", 76)]
with open("scores.csv", "w", newline="", encoding="utf-8") as file:
    writer = csv.writer(file)
    writer.writerow(["name", "score"])
    writer.writerows(scores)

with open("scores.csv", newline="", encoding="utf-8") as file:
    rows = list(csv.reader(file))
print(f"Records: {len(rows) - 1}")
print(f"First: {rows[1][0]} = {rows[1][1]}")

Strip text before validation. Catch ValueError for a bad number; missing fields also need explicit checks. Ignore physically empty CSV rows.

One possible implementation. Check the book's tests and try an extension after comparing.

# Challenge 77 - Read the Reading Log
import csv

records = []
skipped = 0
with open("reading_log.csv", newline="", encoding="utf-8") as file:
    for row in csv.DictReader(file):
        title = (row.get("title") or "").strip()
        duration = (row.get("minutes") or "").strip()
        if not title or not duration:
            skipped += 1
            continue
        try:
            minutes = int(duration)
        except ValueError:
            skipped += 1
            continue
        if minutes <= 0:
            skipped += 1
            continue
        records.append((title, minutes))
print(f"Valid sessions: {len(records)}")
print(f"Total minutes: {sum(minutes for _, minutes in records)}")
print(f"Skipped rows: {skipped}")

Filter records first, then sort by a numeric rating in descending order. Only take the first two sorted records.

One possible implementation. Check the book's tests and try an extension after comparing.

# Challenge 78 - Find Books by Genre
import csv

books = []
with open("books.csv", newline="", encoding="utf-8") as file:
    for row in csv.DictReader(file):
        books.append((row["title"], row["genre"], float(row["rating"])))

wanted = input("Genre: ").strip().casefold()
results = [book for book in books if book[1].casefold() == wanted]
results.sort(key=lambda book: (-book[2], book[0]))
for title, genre, rating in results[:2]:
    print(f"{title}: {rating:.1f}")
if not results:
    print("No books in that genre.")

Place the file-reading statement inside try; handle FileNotFoundError specifically. A folder path has a different error.

One possible implementation. Check the book's tests and try an extension after comparing.

# Challenge 79 - What If the File Is Missing?
from pathlib import Path

name = input("File to read: ").strip()
try:
    text = Path(name).read_text(encoding="utf-8")
except FileNotFoundError:
    print(f"File not found: {name}")
except IsADirectoryError:
    print("Please choose a file, not a folder.")
else:
    print(f"Characters: {len(text)}")

Use append mode and test whether the CSV file already exists. Read it all back into a dictionary of per-subject totals.

One possible implementation. Check the book's tests and try an extension after comparing.

# Challenge 80 - Build a Study Tracker
import csv
from pathlib import Path

path = Path("study_sessions.csv")
subject = input("Subject: ").strip()
try:
    minutes = int(input("Minutes: "))
except ValueError:
    print("Minutes must be a whole number.")
else:
    if not subject or minutes <= 0:
        print("Subject and positive minutes are required.")
    else:
        need_header = not path.exists() or path.stat().st_size == 0
        with path.open("a", newline="", encoding="utf-8") as file:
            writer = csv.writer(file)
            if need_header:
                writer.writerow(["subject", "minutes"])
            writer.writerow([subject, minutes])
        totals = {}
        with path.open(newline="", encoding="utf-8") as file:
            for row in csv.DictReader(file):
                key = row["subject"].strip()
                totals[key] = totals.get(key, 0) + int(row["minutes"])
        for key in sorted(totals):
            print(f"{key}: {totals[key]} minutes")