Jennifer Strejevitch - Feb 2017
Open the command line
+ space then type "terminal"
Look through the menu for your window manager for anything named "Shell" or "Terminal."
With your terminal opened, please type:
➜ ~ whoami
Please observe that in your command line interface there might be a "$" sign or ">". Most examples online will display those signs. You don't need to type them. My terminal displays an arrow for example.
|Windows||Mac OS X or Linux|
|List files and directories||dir||ls|
|Change directory||cd FolderName||cd FolderName|
|Create directory||mkdir FolderName||mkdir FolderName|
|open explorer/finder||start .||open . (Mac)|
Learn more commands on:
Mac OS X
Sublime Text 3... You can choose!
Code editors have lots of helpers such as highlighting, closing quotes for you. They help you read your code better, spot mistakes and most importantly, they produce plain text as opposed to Word, notepad, etc.
Once you have python installed you should be able to get to the python prompt by simply typing "python" on your console. You should then see some information on the version and a ">>>" sign preceding your cursor. Remember that when you are on the python prompt, everything you type will be interpreted as python code, so the directory commands we showed you early won't work. In order to go back to your normal console, type "exit()" then Enter.
You can practice some python commands directly on your console and see some results instantly.
You can practice by following
course = "Python for beginners" students = 40
print("There are " + students + " students in the " + course + " course")
>>> print "There are ", students, " students in the ", course, " course" There are Traceback (most recent call last): File "<stdin>", line 1, in <module> NameError: name 'students' is not defined >>>
Errors happen when you've written something wrong, made a logic mistake or something unexpected happened that made the code operate incorrectly. Generally programming languages have a record of expected errors and can display them to help us find where things went wrong (Like above. We forgot to declare the "students" variable).
def encode(input_string): count = 1 prev = '' lst =  for character in input_string: if character != prev: entry = (prev, count) lst.append(entry) count = 1 prev = character else: entry = (character, count) lst.append(entry) return lst
Python is whitespace sensitive. Its blocks are defined by their indentation. It's a language requirement. I also makes it easier for other people to read your code.
Loops (or iterations) are useful when you need to do something in repetition. One way to do this in Python is through the keyword "for".
for name in "John", "Sam", "Jill": print("Hello " + name)
Hello John Hello Sam Hello Jill
fruits = ["apple", "pear", "oranges", "kiwi"] for fruit in fruits: print(fruit)
Lists are a container of things that are organised in order from first to last.
They are a piece of code that does a determined thing. They help the code be more understandable and avoid repetition.
print() is a function. It does a single thing which is to output to the console.
You can create your own function by using the keyword def
def morning_greeting(): print("Good morning!") >>> morning_greeting() Good morning!
Obs: in order to call a function you need to add () at the end
def morning_greeting(name): print("Good morning " + name + "!") >>> morning_greeting("Jennifer") Good morning Jennifer!
Obs: You might already have noticed that the + sign when used with strings, joins them together. It's commonly called "concatenation".
They allow you to check if something is True or False and take some action based on that
This is possible thanks to the python boolean type. booleans can only hold True or False
>>> 5 > 2 True >>> 10 < 2 False
Both operations above returned a boolean value
direction = -30 if direction > 0 : turtle.forward(direction) else: turtle.left(180) turtle.forward(-direction)
More examples on http://opentechschool.github.io/python-beginners/en/conditionals.html#examples
Suggested exercise: Write a function that takes the time of the day and prints the appropriate greeting. e.g. "Good morning!", "Good night!"...
a = 0 while a < 10: print("The value of the variable a meets the condition since a is " + str(a)) a = a + 1 print("a now is " + str(a)) print("End!")
The value of the variable a meets the condition since a is 0 a now is 1 The value of the variable a meets the condition since a is 1 a now is 2 The value of the variable a meets the condition since a is 2 a now is 3 The value of the variable a meets the condition since a is 3 a now is 4 The value of the variable a meets the condition since a is 4 a now is 5 The value of the variable a meets the condition since a is 5 a now is 6 The value of the variable a meets the condition since a is 6 a now is 7 The value of the variable a meets the condition since a is 7 a now is 8 The value of the variable a meets the condition since a is 8 a now is 9 The value of the variable a meets the condition since a is 9 a now is 10 End!