readability.py

from cs50 import get_string

# Get text from user
text = get_string("Text: ")

# define variables
letters, words, sentences = 0, 1, 0

# Count letters, words and sentences in text
for i in range(len(text)):
    if text[i].lower() in ("abcdefghijklmnopqrstuvwxyz"):
        letters += 1
    if text[i].lower() == " ":
        words += 1
    if text[i].lower() in ("?", "!", "."):
        sentences += 1

# Define parameters for Coleman-Liau
L = (letters / words) * 100
S = (sentences / words) * 100
# Calculate Index per Coleman-Liau
index = round(0.0588 * L - 0.296 * S - 15.8)
# Print Reading Age
if index < 1:
    print("Before Grade 1")
if index > 15:
    print("Grade 16+")
else:
    print(f"Grade {index}")