Stop 06 · Python for Data AnalysisTopics · 1/12

Python Basics for Analysts

In short

Excel starts sweating at a few lakh rows and you can't rerun last week's clicks. A little Python fixes both. You need maybe five ideas, not a computer science degree.

Just enough Python — variables, lists, dictionaries, loops, and functions — to read and write basic analysis scripts, without needing a full software engineering background.

The jaadu arranges a row of colourful spice jars on a kitchen shelf.

Think of it like this

Labelled jars in the kitchen

A variable is a labelled jar: 'sugar' holds a value. A list is the shelf of jars in order. A dictionary is the label-to-jar lookup. A loop is checking every jar one by one, and a function is the recipe you reuse daily.

Watch it happen

A loop walks through a list

420

380

515

290

610

1/5A list of daily sales in rupees: sales = [420, 380, 515, 290, 610]. Positions start at 0, not 1.

The big ideas

What you need to know

Variables and types

A name pointing at a value. Know the four basics: int, float, str (text) and bool (True or False).

Lists and dictionaries

Lists keep things in order, like [10, 20, 30]. Dictionaries map keys to values, like {"city": "Pune", "orders": 42}.

Loops and if

for repeats work over every item. if decides what to do. Together they replace hours of manual checking.

Functions

Wrap steps you repeat into def clean_name(x): and call it anywhere. Less copy-paste, fewer silly mistakes.

See it in code

Walk through the code

python

1sales = [420, 380, 515, 290, 610]2 3total = 04for amount in sales:5    total += amount6    if amount < 300:7        print("Slow day:", amount)8 9def average(values):10    return sum(values) / len(values)11 12print("Total:", total)13print("Average:", average(sales))

1/4A list holds the five daily sales in order.

A tiny script with every basic idea in it. It prints the slow day, then Total: 2215 and Average: 443.0.

Save yourself the pain

Common mistakes

Oops

Mixing tabs and spaces, or forgetting to indent after a colon.

Do this instead

Python uses indentation as structure. Use 4 spaces everywhere; your editor can do it for you.

Oops

Panicking at a red error and closing the notebook.

Do this instead

Read the last line of the error first. It usually names the problem, like NameError or TypeError, and the line number.

Your mission

Your first analysis script

~25 min

Quick check

sales = [420, 380, 515]. What does sales[1] give you?

Go deeper

1Complete a beginner Python course focused on data, not general software development.
2Practice writing a simple script that loops through a list and computes a summary.
3Learn to read Python error messages instead of getting stuck on them.