Pascal's Triangle for Python

Question

As a learning experience for Python, I am trying to code my own version of Pascal\'s triangle. It took me a few hours (as I am just starting), but I came out with this code:

Answer 1

Here is my attempt:

def generate_pascal_triangle(rows):
    if rows == 1: return [[1]]

    triangle = [[1], [1, 1]] # pre-populate with the first two rows

    row = [1, 1] # Starts with the second row and calculate the next

    for i in range(2, rows):
        row = [1] + [sum(column) for column in zip(row[1:], row)] + [1]
        triangle.append(row)

    return triangle

for row in generate_pascal_triangle(6):
    print row

Discussion

• The first two rows of the triangle is hard-coded
• The zip() call basically pairs two adjacent numbers together
• We still have to add 1 to the beginning and another 1 to the end because the zip() call only generates the middle of the next row