Refactored place_twoship

import random

# Convert compass direction to row & column increments
delta = {
    'S': (1, 0),
    'N': (-1, 0),
    'E': (0, 1),
    'W': (0, -1),
}

num_rows = 4
num_cols = 6

def make_board():
    return [['0'] * num_cols for _ in range(num_rows)]

def print_board(board):
    print('\n'.join([' '.join(row) for row in board]), end='\n\n')

def place_twoship(board):
    ship_placed = False
    x = random.randrange(num_rows)
    y = random.randrange(num_cols)
    while not ship_placed:
        direction = random.choice("NSEW")
        dx, dy = delta[direction]
        nx, ny = x + dx, y + dy
        print(x, y, direction, nx, ny)
        if 0 <= nx < num_rows and 0 <= ny < num_cols:
            board[x][y] = "2"
            board[nx][ny] = "2"
            twoshipcord.extend([(x, y), (nx, ny)])
            flippedbattleshipstwo.extend([(y, x), (ny, nx)])
            ship_placed = True

board = make_board()
twoshipcord = []
flippedbattleshipstwo = []

place_twoship(board)
print_board(board)
print(twoshipcord, flippedbattleshipstwo)