Intro to Python

A Tour of Python with Real World Code

Created by jyn using reveal.js

Who's using Python?

Python in 5 minutes

Comparing Python to Java


i = 1
d = 1.2
s = "hello, world"
l = [1, 2, 3]

int i = 1;
double d = 1.2;
String s = "hello, world";
int[] i = {1, 2, 3};

Duck Typing

l = [1, 1.2, "hello, world"]

List<Object> l = Arrays.asList(1, 1.2, "hello, world");

One slide on dictionaries

What's the difference?

d = {0: 'a', 1: 'b', 2: 'c'}
a = ['a', 'b', 'c']
print(d[0])  # prints 'a'
print(a[0])  # prints 'a'

Keys don't have to be integers

d = {'Monday': 'MATH 374', 'Tuesday': 'CSCE 146'}
print(d['Monday'])  # prints 'MATH 374'
Web query parameter example

What's GrepMe?

GroupMe doesn’t have a working search and it made me sad. So I wrote my own in Python!

Yes, I absolutely used this talk to advertise on of my side projects.

What does it look like?

  • Text highlighting
  • Searches in reverse chronological order
  • Can output dates
  • Can search by who liked a message
  • Can search multiple groups at a time

How does it work?

Let's look at the source code
Groupme API Reference

One slide on keyword arguments

What's this do?

def f(**kwargs):
  for key, value in kwargs.items():
    print(key, value)

f(a='b', c='d')  # prints 'a b\nc d'


Compares code in Python to code that does the same thing in Java

  1. printing to the console
  2. for-each loops
  3. generics
  4. doc-comments
  5. varargs
  6. lambdas

Printing to the console

print("Hello, world!")

System.out.println("Hello, world!");

For-Each loops

  for i in [1, 2, 3]:

  for (int i : Arrays.asList(1, 2, 3)) {


Python doesn't have generics, or rather, everything is generic! It uses duck-typing instead.

def makeList(element):
  return [element]

<T> List<T> makeList(T element) {
  ArrayList<T> myList = new ArrayList<T>();
  return myList;

Documentation Comments

This documents the function 'my_function'

Longer descriptions go here, in plain text
def my_function():
  return 4  # guaranteed by IEEE to be random

 * This documents the function 'my_function'

Longer descriptions go here, in HTML markup

* @return A random integer between 0 and 1000 */ int my_function() { return 4; }

Variadic Arguments

def print(*args):
  for arg in args:

void print(Object ... args) {
  for (Object arg : args) {

First-Class and Anonymous Functions

def call_with_one(f):
  return f(1)

call_with_one(lambda arg: print(arg))

void call_with_one(IntConsumer f) {
call_with_one(i -> System.out.println(i));