PyKarel

A Python-based educational programming language inspired by Karel

https://en.wikipedia.org/wiki/Karel_(programming_language)

Resources

• Introduction
• Getting Started
• Wiki
• API Reference
• Examples

Installation

1. Download and install Python 3 from the official website https://www.python.org/downloads/
2. Extract the latest release of PyKarel https://github.com/cpiehl/pykarel/releases/latest

Introduction

Karel is a triangular robot that lives in a 2-dimensional grid world like this:

######################
#                    #
#                    #
#                    #
#                    #
#                    #
#                    #
#                    #
#     ▲              #
#                    #
#                    #
######################

In the world there are round objects called Beepers. Karel can pick these up to move them around.

#######
#     #
# ► o #
#     #
#######

Karel has 4 basic commands to interact with the world:

move() # moves forward one space
turnleft() # turns 90 degrees left
pick_beeper() # picks up a beeper and puts it in Karel's beeper storage
put_beeper() # puts down a beeper from Karel's beeper storage

In order to safely interact with the world, Karel also has 3 commands to learn about its surroundings:

front_is_clear() # checks if Karel can safely move forward
check_beeper() # checks if a beeper is in front of Karel
beeper_count() # returns the number of beepers in karel's beeper storage

Getting Started

Every PyKarel program must start with

import Karel

Create a Karel robot at coordinates X=1, Y=1, facing South

import Karel
karel = Karel.Robot(1, 1, Karel.SOUTH)

Create a World by loading a World file and add karel to it

import Karel
karel = Karel.Robot(1, 1, Karel.SOUTH)
world = Karel.World("worlds/10x20-room-closed.txt")
world.add_robot(karel)

Move Karel forward one space, turn left 90 degrees, then move forward again

import Karel
karel = Karel.Robot(1, 1, Karel.SOUTH)
world = Karel.World("worlds/10x20-room-closed.txt")
world.add_robot(karel)

karel.move()
karel.turnleft()
karel.move()

But be careful! Karel could become damaged if it rams into a wall at full speed! It is a good idea to check if it can safely move first.

if karel.front_is_clear():
  karel.move()
karel.turnleft()
if karel.front_is_clear():
  karel.move()

Lastly, Karel is programmable to accept more complex commands! A common addition is telling Karel how to turn right:

import Karel

def turnright():
  karel.turnleft()
  karel.turnleft()
  karel.turnleft()
  
karel = Karel.Robot(1, 1, Karel.SOUTH)
world = Karel.World("worlds/10x20-room-closed.txt")
world.add_robot(karel)

if karel.front_is_clear():
  karel.move()
karel.turnleft()
if karel.front_is_clear():
  karel.move()
turnright()
if karel.front_is_clear():
  karel.move()