Glossary

Plain-English definitions of every Python and Excel-meets-Python term used in the course. Bookmark it.

A

Anaconda — A bundled installer that gives you Python plus the most common data-science libraries (pandas, NumPy, Jupyter) all in one go. The easiest way for an Excel user to get a full Python setup. (Module 02)

Argument — A piece of data you hand to a function. In round(3.14, 1) the arguments are 3.14 and 1. Same idea as the inputs you give to an Excel formula.

Array — An ordered collection of values. In Python the everyday version is called a list. NumPy adds a specialized array type for fast math.

B

Boolean — A value that's either True or False. Excel calls them TRUE/FALSE; Python uses the same idea, capitalized differently.

Bug — A mistake in your code that makes it behave unexpectedly. Fixing bugs is called debugging.

C

Cell (Excel) vs Variable (Python) — In Excel a cell holds a value; in Python a variable holds a value. A1 = 100 in Excel becomes a1 = 100 in Python.

Comment — Text in your code that Python ignores. Starts with #. Useful for notes to yourself or future-you.

Conditional — A piece of code that runs only if a condition is true. The Python if/elif/else family. Same as Excel's IF().

CSV — Comma-Separated Values. A plain-text spreadsheet that any tool on earth can open.

D

DataFrame — Pandas' name for a table — rows and columns, just like an Excel sheet. (Module 09)

Dictionary (dict) — A lookup table inside Python. Like XLOOKUP baked into the language. Stored as {"key": value}.

Docstring — A short description at the top of a function explaining what it does. Triple-quoted.

E

Environment — A self-contained installation of Python and a chosen set of libraries. You can have several on one computer without them stepping on each other.

Exception — Python's word for an error that stops your script. NameError, ValueError, FileNotFoundError are common ones.

F

Function — A reusable piece of code that takes inputs (arguments) and gives back an output. Like a custom Excel formula but more flexible. (Module 05)

For loop — A way to repeat code for every item in a collection. "For every row in this table, do X."

I

IDE — Integrated Development Environment. A code editor with extras. VS Code is the one this course uses. (Module 02)

Import — The Python statement that loads a library so you can use it. import pandas.

Indentation — Python uses leading spaces to group code. Four spaces per level. Get the indentation wrong and Python refuses to run the code.

J

Jupyter notebook — A document that mixes code, output, and notes. Great for exploring data. (Module 02)

L

Library — A pre-written bundle of code you can use. Pandas, NumPy, openpyxl, matplotlib. Same idea as an Excel add-in.

List — An ordered, editable sequence of values. Written with square brackets: [10, 20, 30].

M

Method — A function attached to an object. Strings have methods like .upper(); DataFrames have methods like .groupby().

Module — A single Python file that you can import. Lots of modules grouped together make a library.

N

NumPy — A library for fast numerical math. Pandas is built on top of it.

O

openpyxl — The Python library that reads and writes Excel .xlsx files. (Module 07)

Object — Anything you can store in a variable in Python. Numbers, strings, lists, DataFrames — they're all objects.

P

Pandas — The library that makes Python feel like a souped-up Excel. The most important library in this course. (Module 09)

Pip — Python's package installer. pip install pandas downloads pandas from the internet and sets it up for you.

PY function — =PY() inside an Excel cell — runs Python and returns the result. (Module 08)

R

REPL — Read–Eval–Print Loop. The interactive Python prompt where you type one line and get an answer back. Great for trying things.

S

Script — A file ending in .py that contains Python code you can run.

Series — A single column of a pandas DataFrame.

String — Text. Wrapped in quotes: "hello" or 'hello'.

T

Terminal / Command line — The text-based interface to your computer. Macs call it Terminal; Windows calls it PowerShell or Command Prompt. (Module 02)

Tuple — Like a list, but you can't change it after you make it. Written with parentheses: (10, 20).

V

Variable — A named container for a value. price = 99 creates a variable called price.

Virtual environment (venv) — A self-contained Python setup for a single project. Stops different projects from clashing.

W

While loop — Repeat code as long as a condition is true. "While there are still rows to process, keep going."