Python Basics¶

Python is widely used because it is readable, versatile, and supported by a large ecosystem of scientific and general-purpose libraries. In RECODE, we use it as the common language for examples, exercises, and small research tools.

Ways to run Python¶

You will encounter Python in three common forms:

Interactive terminal for quick experiments,
scripts for repeatable code stored in .py files,
notebooks for teaching, exploration, and mixed text/code workflows.

Each one is useful. What matters is recognizing when to use which format.

Variables and names¶

Variables store values so you can reuse them later:

temperature_c = 23.5
sample_name = "alloy_A"
is_valid = True

Choose names that describe the meaning of the value, not just its type. sample_name is better than x, and is_valid is better than flag1.

Core data types¶

Some common Python data types are:

str for text,
int for whole numbers,
float for decimal numbers,
bool for True / False,
complex for complex numbers.

You can inspect a value's type with:

value = 3.14
print(type(value))

Expressions and operators¶

Python follows standard mathematical rules for many operations:

3 + 4
3 ** 4
2 + 3 - 4 * 5 / 2

Parentheses help make intent explicit:

a = 3 ** 4
result = a * (3 + 4 * (5 + 6))

Functions¶

Functions let you name a reusable action:

def calc_square(x):
    return x ** 2

You can then call the function with different inputs:

print(calc_square(5))
print(calc_square(12))

Functions are one of the first major steps from "typing commands" to "writing programs."

Basic imports¶

Python's standard library already contains many helpful tools:

import math

print(math.sqrt(81))

External libraries add more capabilities:

import numpy

print(numpy.sqrt(49))

This is a common pattern in scientific Python: start with core language features, then bring in specialized libraries when the problem requires them.

Notebooks as a learning tool¶

The introductory notebook in the repository shows a useful teaching pattern:

write a small code cell,
run it immediately,
inspect the result,
modify one thing and run it again.

That feedback loop is especially effective when learning basics such as:

printing values,
checking data types,
comparing lists and arrays,
plotting simple results.

Practice ideas¶

Try the following on your own:

Create three variables with different types.
Write a function that converts Celsius to Kelvin.
Import math and calculate a square root.
Print a sentence that includes both text and a number.

The point is not complexity. The point is building fluency with the syntax.