Basic Operators and Data Structures in Python

Python For Loops

Key Points

  1. Repeating a Process Using a For Loop

    • A for loop iterates over each element of a list:
    row_1 = ['Facebook', 0.0, 'USD', 2974676, 3.5]
for element in row_1:
    print(element)

  2. Appending Values to a List

    • Use .append() to add values to a list:
    a_list = [1, 2]
a_list.append(3)  # [1, 2, 3]

  3. Opening a Dataset File and Creating a List of Lists

    • Use csv to read files:
    opened_file = open('AppleStore.csv')
from csv import reader
read_file = reader(opened_file)
apps_data = list(read_file)

  4. Converting a String to a Float

    • Combine loops and type conversion to process data:
    rating_sum = 0
for row in apps_data[1:]:
    rating = float(row[7])
    rating_sum += rating

  5. Key Concepts

    • For Loops automate repetitive processes.

    • A for loop starts with the for keyword and iterates over an iterable variable:

      for element in app_ratings:
    # Code block (indented)
    • The iteration variable (element) takes on a new value for each iteration.
    • If the iterable (e.g., a list) has three elements, the loop body executes three times.

  6. Python Keywords

    • for and in are examples of Python keywords.

Summary

Additional Resources