Python is a programming language.

It’s the code you write.

somevariable = 5 + 6

Jupyter is a program, an “integrated development environment” (IDE).

You can write Python in different places, but in this class we will write and run Python inside Jupyter Lab.

Jupyter Lab lets you see and access files on your computer.

Files are organized in a hierarchy of directories.

Variables store information

myvar = 5

myvar #or print(myvar)

You Try It!

Create a variable called “newVar” that is equal to the value of five plus seven. Then display your variable to see what its value is.

Use descriptive variable names, and avoid spaces.

i_use_snake_case
otherPeopleUseCamelCase
some.people.use.periods
And_aFew.People_RENOUNCEconvention

Add frequent comments to explain what your code does.

Comments in Python begin with a # symbol.

# This variable contains a continuous value
some_variable = 2.5

You should also use comments for citations!

Variables have types.

• String or Character: a piece of text (ex. "five")
• Integer: a discrete numerical value (ex. 5)
• Float or Double: a continuous numerical value (ex. 5.0)

stringvar = "five"

type(stringvar)

You can put reusable code in Jupyter Notebooks.

These are “.ipynb” files, and you can create them by clicking the + icon at the top left of the Jupyter Lab window and selecting a Python 3 notebook.

Always comment your code so you can remember things when you come back later!

A list is surrounded by brackets and can contain any kind of data.

mylist = [5,6,7]

secondlist = ["cat","dog","fish"]

# Access items in a list
mylist[0]
secondlist[1]

A dictionary is surrounded by braces and contains key/value pairs.

mydictionary = {"pet_name": "Fido", "age": 5, "pet_type": "dog"}

# Access items in a dictionary
mydictionary["pet_name"]
mydictionary["age"]

A function is a command that runs based on some input or parameter.

Python has many built-in functions.

# Some functions give a number result
sum([5,6,7])
mylist = [5,6,7]
sum(mylist)
len(mylist)

# But functions can do anything! 
type(mydictionary)

Functions can do just about anything: calculate values, create graphs, transform data, etc.

You can create functions like you create variables.

def myfunction(arg1, arg2, ... ):
    statements
    return object

A real example:

def get_last_value(some_list):
  return some_list[len(some_list) - 1]

# But you can do this with some_list[-1]

You can use the for operator to iterate through a list.

mylist = [5,6,7,8]
for item in mylist:
  addone = item + 1
  print(addone)

You can use if and else to set conditions.

# Let's use the range() function to make a list
newlist = range(1,11) 
for i in newlist:
  if i-5 == 0:
    print("It's five!")
  elif i-5 == 5:
    print("It's ten!")
  else:
    print("Nope, try again...")

Libraries/Packages contain reusable functions made by someone else.

# Install libraries only once in the Terminal 
pip install packagename

# Import a library every time you run your code
import packagename

# You can also rename packages to make it easier
import packagename as pn

You Try It!

Import the pandas package and abbreviate it pd. If it works, there will be no output!

All this and more in Chapters 2 & 3 of Python for Data Analysis!