Stop 01 · Programming & CS FoundationsTopics · 1/12

Python Syntax & Data Types

In short

Every AI model you will ever train starts as plain Python: numbers, text, lists and dictionaries. Get comfortable with these few building blocks and the rest of AI code stops looking scary.

Python is the default language of AI engineering — its syntax, numbers, strings, lists, tuples, dicts and sets are the building blocks of every notebook, script and model you'll write.

The purple blob sorts rice and spices into different jars and steel containers on a kitchen shelf.

Think of it like this

Containers in an Indian kitchen

Rice goes in a big tin, salt in a small jar, spices in the masala dabba with its own little bowls. Each container suits what it holds. Python types work the same way: int for whole numbers, str for text, list for a row of things, dict for labelled things.

Watch it happen

One value per type

3.14

'chai'

True

None

[1, 2]

{'a': 1}

1/542 is an int, a whole number. Python ints never overflow, so 2 ** 100 just works.

The big ideas

What you need to know

Variables are just name tags

x = 5 sticks the name x on the value 5. Later x = 'hi' moves the tag to a string. No type declarations needed.

Lists change, tuples don't

A list [1, 2] can grow and shrink. A tuple (1, 2) is fixed, which makes it safe to use as a dict key.

Dicts look things up fast

marks['riya'] finds Riya's marks instantly, no matter how many students are stored. You'll use dicts constantly for configs and JSON.

Sets remove duplicates

set(['a', 'b', 'a']) keeps one 'a'. Handy for finding unique labels in a dataset.

See it in code

Walk through the code

python

1name = "Riya"            # str2age = 20                 # int3cgpa = 8.7               # float4is_topper = cgpa > 9     # bool -> False5 6skills = ["python", "sql"]          # list7skills.append("pandas")8 9student = {"name": name, "age": age, "skills": skills}  # dict10print(student["skills"][0])        # python11print(type(cgpa), len(skills))     # <class 'float'> 312 13tags = {"ml", "ai", "ml"}          # set14print(tags)                        # {'ml', 'ai'} (order may vary)

1/4Simple types. Python works out the type from the value, so no int or string keyword is needed.

Five lines of setup cover nearly every type you'll meet in a data script. type() tells you what you're holding when you're unsure.

Save yourself the pain

Common mistakes

Oops

Writing true, false or null like in JavaScript.

Do this instead

Python uses True, False and None, with capital letters. Lowercase versions are just undefined names.

Oops

Comparing floats with == and being surprised, like 0.1 + 0.2 == 0.3 returning False.

Do this instead

Use math.isclose(a, b) or round both sides when you compare decimal results.

Your mission

Describe yourself in Python

~15 min

Quick check

You need to store each student's roll number with their marks and look marks up by roll number. Which type fits best?

Go deeper

1Work through a Python fundamentals course or the official Python tutorial end to end.
2Practice converting between data types and predicting output before running code.
3Write small scripts that manipulate lists, dicts and strings without looking up syntax.