Karel's Built in Commands
# Paints a square red. paint(color['red']) # Colors: color['red'] color['blue'] color['green'] color['yellow'] color['cyan'] color['orange'] color['white'] color['black'] color['gray'] color['purple'] # Determine if a square is a certain color if color_is(color['red']): move()
# Returns true 50% of the time random_chance() # Returns true probability percentage of the time random_chance(probability) # Returns true 20% of the time. random_chance(0.2) # Example if random_chance(0.8): put_ball()
Writing a Function
Writing a function is like teaching karel a new word.
Naming Functions: You can name your functions whatever you want, but you can't have spaces in the function name.
Remember that commands in functions must be indented one level
def turn_right(): turn_left() turn_left() turn_left() def turn_around(): turn_left() turn_left() def your_function_name(): # Code that will run when you make a call to # this function.
Calling a Function
You call a function to tell the computer to actually carry out the new command.
# Call the turnn_around() function once turn_around() # Call the turn_right() function 2 times turn_right() turn_right()
Conditional StatementsRemember that comands in conditional statements must be indented one level.
if condition: #code that will run if the condition is true
if condition: #code that will run if the condition is true else: #code that will run if condition is not true
Example of if statements
if front_is_clear(): move() if balls_present(): take_ball() else: move()
Karel ConditionsDon't forget the
()at the end!
front_is_clear() left_is_clear() right_is_clear() facing_north() facing_south() facing_east() facing_west() balls_present()
front_is_blocked() left_is_blocked() right_is_blocked() not_facing_north() not_facing_south() not_facing_east() not_facing_west() no_balls_present()
LoopsRemember that commands in a loop statement must be indented one level.
while CONDITION: # Code that will run while the CONDITION is true. # Once the CONDITION is no longer true, # it will stop.
Example of while loops
# This moves Karel to a wall while front_is_clear(): move()
for i in range(COUNT): # Code that will run 'COUNT' times
Example of for loops
# This puts down 10 balls */ for i in range(10): put_ball()You can have multiple statements or function calls in a for loop.
# This puts down five balls and moves after each one for i in range(5): put_ball() move()
Use for-loops when you want to repeat something a fixed number of times.
Use while-loops when you want to repeat something as long as a condition is true.
""" A multi-line comment describes your code to someone who is reading it. """ # Use single line comments to clarify code.