pyPython cheatsheet

print("Score:", score)

print puts a space between values and a new line at the end.

name = input("Name? ")

input always gives back a string, even when someone types digits.

age = int(text)
price = float(text)

Turn text into a whole number or a decimal.

# a comment

Python ignores everything after a hash.

f"{name} has {hp} HP"

An f-string puts values inside text.

s.upper(), s.lower(), s.strip()

Change case, trim spaces. Each method returns a new string.

s.split(), " ".join(words)

Text to a list of words, and a list of words back to text.

s[0], s[-1], s[:3], len(s)

First character, last character, first three, length.

"gg" in message

True if the text appears anywhere in the string.

7 / 2, 7 // 2, 7 % 2

3.5, then whole number division (3), then the remainder (1).

2 ** 10

Powers: 2 to the 10th is 1024.

round(3.14159, 2)

Rounds to 2 decimal places: 3.14.

f"{price:.2f}"

Show a number with exactly 2 decimal places.

if hp <= 0:
    print("Game over")
elif hp < 20:
    print("Low HP")
else:
    print("Fine")

Python checks each condition in order and runs the first one that is true.

==, !=, <, <=, >, >=

Compare values. One = stores, two == compares.

if age >= 13 and not banned:

Combine conditions with and, or, not.

for song in playlist:
    print(song)

Runs once per item.

for i in range(1, 11):

The numbers 1 to 10. The end number is left out.

for i, song in enumerate(playlist):

Gives the position and the item together.

while lives > 0:

Repeats as long as the condition is true.

break, continue

Leave the loop now, or skip to the next pass.

squad = ["Ana", "Ben"]
squad.append("Cleo")

Make a list and add to the end.

squad[0], squad[-1], squad[1:3]

First item, last item, a slice.

squad.remove("Ben"), squad.pop()

Remove by value, or remove and return the last item.

sorted(scores), scores.sort()

A new sorted list, or sort this list in place (which returns None).

sum(scores), max(scores), len(scores)

Total, biggest, count.

stock = {"potion": 3, "arrow": 20}

Keys on the left of each colon, values on the right.

stock["gem"] = 1

Add a key, or replace its value.

stock.get("shield", 0)

Read a key with a fallback instead of a KeyError.

for item, n in stock.items():

Loop over keys and values together.

"potion" in stock

Checks the keys.

def area(w, h):
    return w * h

Parameters in, one value back out with return.

def greet(name, loud=False):

A default value makes that argument optional.

greet("Ana", loud=True)

Pass an argument by name.

total = area(3, 4)

Catch what a function returns. With no return you get None.