Python Coding challenge - Day 1188| What is the output of the following Python Code?

 

Code Explanation:

🔹 1. Importing defaultdict

from collections import defaultdict

✅ Explanation:

defaultdict is imported from Python's collections module.

It automatically creates a default value when a missing key is accessed.

Normal dictionary:

d = {}

d["x"]

Output:

KeyError

But defaultdict avoids this error.

🔹 2. Creating a defaultdict

d = defaultdict(set)

✅ Explanation:

Here:

set

is passed as the default factory.

Meaning:

Whenever a missing key is accessed,

automatically create an empty set.

Current state:

defaultdict(set, {})

Visual:

d

↓

{}

🔹 3. Accessing Key "x"

d["x"]

✅ Explanation:

Python checks:

Does key "x" exist?

Answer:

No ❌

Since it's a defaultdict(set):

Python automatically creates:

set()

which is:

{}

(Empty Set)

Current state:

{

    "x": set()

}

🔹 4. Adding Value to Set

d["x"].add(1)

✅ Explanation:

Current set:

set()

Add:

1

Set becomes:

{1}

Current dictionary:

{

    "x": {1}

}

🔹 5. Accessing Key Again

d["x"]

✅ Explanation:

Now key already exists.

Python finds:

{1}

No new set is created.

🔹 6. Adding Same Value Again

d["x"].add(1)

✅ Explanation:

Attempt to add:

1

again.

But sets follow the rule:

Duplicate values are not allowed

Current set:

{1}

After adding:

{1}

No change.

🔹 7. Final Dictionary State

{

    "x": {1}

}

Visual:

d

│

└── x

      ↓

     {1}

🔹 8. Printing the Set

print(d["x"])

✅ Explanation:

Python accesses:

d["x"]

Value:

{1}

Prints:

{1}

🎯 Final Output

{1}

Book:

Application of Python in Audio and Video Processing