Python Reference

A practical guide to the Python syntax, built-in functions, and programming concepts used in everyday development.

Variables & Data Types

Variables

Store data that can be used and updated throughout a program.

trail_name = "Eagle Peak"
elevation = 2450
has_bear = True

type() & Conversion

Check a value’s type or convert it to another data type.

type(trail_name)
int("850")
str(42)
float("12.7")

Constants (convention)

Python doesn’t enforce constants, but uppercase names are the standard convention.

MAX_GROUP_SIZE = 12

Output & Input

print()

Displays text or variable values in the console.

print("Trail:", trail_name, "Elevation:", elevation, "m")

input()

Reads input from the user and returns it as a string.

difficulty = input("How difficult is the trail? ")

f-strings

Insert variables directly into strings using readable syntax.

f"Welcome to {trail_name}! Elevation: {elevation}m"

Numbers & Math

Operators

Perform mathematical calculations with numbers.

distance + 4.2
total_time - 30
elevation * 2
distance / 5
hours // 2
steps % 1000
2 ** 4

Built-in Math Functions

Built-in functions for common mathematical tasks.

round(12.78)
abs(-450)
max(1200, 2450, 890)
min(5, 18, 3)
sum([4, 7, 12])

import math

Provides additional mathematical functions and constants.

import math
math.sqrt(225)
math.pi

Strings

String Methods

Modify, search, or format string values.

trail.upper()
"  muddy path  ".strip()
description.replace("bear", "deer")
"lake,forest,peak".split(",")

len() & Checking

Measure string length or check whether a value exists.

len("Waterfall Trail")
"rain" in forecast

Conditions

if / elif / else

Run different code depending on whether conditions are true or false.

if elevation >= 2000:
    print("High altitude trail!")
elif weather == "Rain":
    print("Trail may be slippery")
else:
    print("Good conditions")

Comparisons & Logic

Compare values and combine conditions with logical operators.

distance >= 10 and has_water == True

Loops

for Loop

Repeat code for each item in a sequence.

for i in range(1, 6):
    print("Checkpoint", i)

for animal in wildlife:
    print(animal)

while Loop

Repeat code while a condition remains true.

while energy > 0:
    energy -= 10

Control Statements

Control how loops behave during execution.

break
continue

Functions

def

Create reusable blocks of code that perform specific tasks.

def calculate_pace(distance, time):
    return distance / time

Lambda

Create small anonymous functions in a single expression.

double = lambda x: x * 2
is_steep = lambda slope: slope > 20

Lists

List Basics

Store ordered collections of items that can be modified.

trails = ["Pine Ridge", "Lake View"]
trails.append("Summit Loop")
trails.pop()
len(trails)

List Comprehensions

Create new lists using a compact, readable syntax.

elevations = [x * 100 for x in range(5)]

Common Methods

Frequently used methods for managing list data.

distances.sort()
sorted(distances)

Dictionaries

Dictionary Basics

Store related information as key-value pairs.

trail = {
    "name": "Bear Canyon",
    "length": 14.5,
    "difficulty": 7
}
trail["water"] = True

Dictionary Methods

Access or work with dictionary data.

trail.keys()
trail.get("difficulty")
for key, value in trail.items():

File Handling

Reading & Writing

Read from or write to files using context managers.

with open("trails.txt", "r") as f:
    data = f.read()

with open("log.txt", "w") as f:
    f.write("Hike completed!")

Modules & Imports

import

Load Python modules so their features can be used.

import random
import math
from datetime import date

Popular Built-ins

Frequently used standard library modules.

random.randint(1, 20)
math.sqrt(64)

Error Handling

try / except / finally

Handle runtime errors without stopping the program.

divisor = 0
try:
    result = distance / divisor
except ZeroDivisionError:
    print("Cannot divide by zero!")
finally:
    print("Hike log saved")