Setup
Virtual Env
python3 -m venv <desired-path>
# Activate the virtualenv:
source <desired-path>/bin/activate
# Deactivate the virtualenv:
deactivate
# Install packages with pip3
pip install Cython==0.27.3
pip install kivy
Install pip package for user only
This will install pip package to $HOME/.local/bin/<pip_package>
pip install --user <pip_package>
Lists
Advanced Lists Contains list of values (integers, strings, variables, other lists, dictionaries). Each item in the list has an index number assigned to it, starting at 0
my_list = ["string1", 2, var, "string2"]
print(my_list[0]) # Print first item in the list
print(my_list) # Print contents of the my_list
for item in my_list:
print(item) # Loop through each item in the list
# Results:
string1
2
var
string2
# Append to list:
my_list.append("value") # Append value to the list
Removing elements from lists n.pop(index) will remove the item at index from the list and return it to you:
n = [1, 3, 5]
n.pop(1)
# Returns 3 (the item at index 1)
print n
# prints [1, 5]
n.remove(item) will remove the actual item if it finds it:
n.remove(1)
# Removes 1 from the list,
# NOT the item at index 1
print n
# prints [3, 5]
del(n[1]) is like .pop in that it will remove the item at the given index, but it won't return it:
del(n[1])
# Doesn't return anything
print n
# prints [1, 5]
Dictionaries
my_dictionairy = { "key1":"value1", "key2": "value2" }
for key in dictionairy:
print(key) # Print dictionairy keys
print(dictionairy[key]) # Print the values associated with those keys
# Results
key1
key2
value1
value2
Change or Add elements in dictionairy
my_dict = {'name':'Jack', 'age': 26}
my_dict['age'] = 27 # Update value
print(my_dict) # Output: {'age': 27, 'name': 'Jack'}
my_dict['address'] = 'Downtown' # Add item
print(my_dict) # Output: {'address': 'Downtown', 'age': 27, 'name': 'Jack'}
Functions
def add_function(x, y): # Create function called add_function
return x + y # Function should return sum of x and y
n = "Hello" # Define string
def string_function(s): # Define function that take variable s
return str(s) + "world" # Function joins variable s with word "world"
print(string_function(n)) # Print function with variable n
# Result:
Helloworld
Useful Methods
.join()
letters = ['a', 'b', 'c', 'd']
print " ".join(letters)
print "---".join(letters)
# OUTPUT
a b c d
a---b---c---d
Lambda syntax
Same as defining a function but without giving it explicit name
lambda x: x % 3 == 0 # Return x if divisible by 3 (modulo)
def by_three(x): # Function "by_three"
return x % 3 == 0 # Return x if divisible by 3 (modulo)
Example
languages = ["HTML", "JavaScript", "Python", "Ruby"]
# Add arguments to the filter()
print filter(lambda x: x == "Python", languages)
# => ['Python']
squares = [i ** 2 for i in range(1,11)] # Squares of numbers 1 to 10
print(filter(lambda x: x > 30 and x <= 70, squares)) # print out only the squares that are between 30 and 70 (inclusive)
# => [36, 49, 64]
File I/O
Automatically close file after reading/writing
with open("file", "mode") as variable:
# Read or write to the file