GeneralPythonSnippets

This is a crash course in the Python subset. If you already master these you should not waste time reading this, unless you want to check for typos or factual inaccuracies.

basic 1	basic 2	intermediate
print	string manipulation	decorators
integer	for loop
float	list comprehensions
string	while loop
tuple	flow control
list	try except
dictionary	functions
boolean	import libraries
if statements	classes
standard library

How to run this code

(elaborate) : Open Blender, and get a Python console view open. You'll notice >>> , this is a prompt waiting for you to type stuff. What we'll be doing below is type stuff after the prompt, then hit Enter to run it.

###print

While you learn Python print() is your friend. It will try to display whatever is between the parenthesis ( ).

>>> print("Hello apprentice")
... Hello apprentice

I'll return to print() frequently on this page to show how to display information that you will find helpful while coding.

###integer

Whole numbers, positive or negative. You'll see plenty of these as you progress.

# let's make a variable called hal
>>> hal = 3000
>>> print(hal * 3)
... 9000

###float

Numbers like these 100.0, 0.0000003 and 34.4. etc. You will often see unusual floats like 0.00200023423 when you expect to see just 0.002, this is normal and will be explained later.
You might also see scientific notation for small numbers namely 2e-7 which is equivalent to 0.0000002.

A lot more can be said about floats but it rarely makes sense to talk about them in isolation. You'll see more references to floats further down.

###string

The words you read right now are strings. In Python we express strings by wrapping them in single qoutes, double qoutes or tripple qoutes.

>>> my_first_string = "I am a HAL 9000 computer"
>>> my_second_string = 'I am a HAL 9000 computer'
>>> my_third_string = """I am a HAL 9000 computer"""

You can add strings together, we call it 'concatenation':

# notice the spaces at the end of string, why is that?
>>> var1 = "I am a "  
>>> var2 = "HAL "
>>> var3 = "9000 computer"
>>> print(var1 + var2 + var3)
... I am a HAL 9000 computer

to convert a non string to a string is done explicitly using str():

>>> some_number = 9000
>>> "Hal " + str(some_number) 
... "Hal 9000"`

Further string manipulation is discussed at a later stage. Strings are used a lot in Python, but in Blender they're commonly used to name objects, data, or set the properties of data.

###tuple

This is a data type which is used to collect data. You'll see a tuple defined in various ways.

>>> some_number = 20
>>> tuple_one = ('some_string', some_number, 0.3444)
... ('some_string', 20, 0.3444)

but it's OK to drop the surrounding parenthesis, the comma separator is most important

>>> tuple_two = 'some_string', some_number, 0.3444
>>> tuple_two
... ('some_string', 20, 0.3444)

you'll also see it written this way, but it is not common.

>>> tuple_three = tuple(['some_string', some_number, 0.3444])

A tuple is immutable. This means you can not change any of the members of the tuple, once it's created it is unchangeable - also if the tuple was made with variables. If you change a variable, the tuple's content is not updated.. see what happens when we update var2 to hold a new string SAL .

>>> var1 = "I am a "
>>> var2 = "HAL "
>>> var3 = "9000 computer"
>>> tuple_four = var1, var2, var3
>>> tuple_four
... ('I am a ', 'HAL ', '9000 computer')
>>> var2 = 'SAL '
>>> var4
('I am a ', 'HAL ', '9000 computer')    

To change a tuple you must assign a new tuple by overwriting the tuple stored in var4.

>>> var4 = (var1, var2, var3)
>>> var4
('I am a ', 'SAL', '9000 computer')