Functions

function

• Function ek named sequence of statements hota hai jo ek specific kaam (operation) karta hai.

• Simple words mein, function ek code block hai jise ek name diya jaata hai.

• Jab bhi us kaam ki zarurat ho, us name se function ko call kar sakte ho.

• Isse same code baar-baar likhna nahi padta.

Easy AI/ML/DS Example

• Maan lo tumhe har Dataset ka average nikalna hai.

• Ek function bana do jo average calculate kare.

• Ab usi function ko alag-alag Datasets ke liye baar-baar use kar sakte ho.

Python Example

print(type(32))

Output

<class 'int'>

Explanation of the Example

• type function ka name hai.

• () ko parentheses kehte hain. Inke andar jo value dete hain, use argument kehte hain.

• Yahan 32 ek argument hai.

• Argument wo value hoti hai jo hum function ko dete hain, taaki function us par kaam kar sake.

• Yahan type() function 32 ka data type check karta hai aur batata hai ki 32 ek int hai.

Yaad rakhne ki Trick

• Function = Named code + Argument = Data jo function ko diya jaata hai.

User-Defined Function

• User-Defined Function wo function hota hai jo programmer khud banata hai

• Ye ek unique block of code hota hai jo sirf call karne par execute hota hai aur ek specific task perform karta hai.

• Jab Python mein koi kaam pehle se available na ho ya apna custom kaam karwana ho, tab hum apna function banaate hain.

• User-Defined Function ko def keyword se create kiya jaata hai.

Easy AI/ML/DS Example

• Maan lo tum har Dataset ke marks mein 5 bonus marks add karna chahte ho.

• Iske liye tum ek User-Defined Function bana sakte ho aur usse baar-baar use kar sakte ho.

Python Example; function bangaya

def even_odd(num):
  if num % 2 == 0:
    print("Even")
  else:
    print("Odd")

lets try

even_odd(100)

Output - Even

Yaad rakhne ki Trick

• User-Defined Function = Jo function programmer khud banata hai.

Lambda Function

• Lambda Function ek small, anonymous function hota hai.

• Anonymous ka matlab hai iska koi name nahi hota.

• Jab sirf ek chhota sa kaam karna ho, tab Lambda Function use karte hain.

• Lambda Function ko lambda keyword se banaya jaata hai.

• Ye short aur one-line function hota hai.

• Isse chhote kaam ke liye alag se def function likhne ki zarurat nahi padti.

• Isse code short, clean, aur padhne mein easy ho jaata hai.

• Ye kitne bhi arguments le sakta hai, lekin isme sirf ek expression hi likh sakte hain.

• syntax - lambda arugument: expressions

Easy AI/ML/DS Example

• Maan lo tumhe Dataset ke har employee ki salary aur bonus ko add karke total nikalna hai.

• Is chhote calculation ke liye tum Lambda Function use kar sakte ho.

Python Example

total_salary = lambda salary, bonus: salary + bonus

print(total_salary(50000, 5000))

Output

55000

Another example -

x = lambda a: "even" if a % 2==0 else "odd"
print(x(6))

odd

• Function = Naam ke bina, one-line function jo many arguments le sakta hai, but sirf ek expression likh sakte ho.

Factorial

FactorialMeaning

Factorial ka matlab hai kisi number ko 1 se us number tak ke sabhi numbers se multiply karna.

Example:

5! = 1 × 2 × 3 × 4 × 5 = 120

Ya is tarah bhi likh sakte hain:

5! = 5 × 4 × 3 × 2 × 1 = 120

Dono same answer dete hain.

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Why do we use Factorial?

Factorial ka use Combinations, Permutations, Probability, Mathematics, Data Science aur Machine Learning mein hota hai.

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Python Example

def fact_number(n):
    fact = 1

    for i in range(1, n+1):
        fact = fact * i

    return fact

fact_number(5)

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Easy Explanation

def fact_number(n):

Hum ek Function bana rahe hain jo kisi number ka factorial calculate karega.

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fact = 1

Ek variable banaya jisme final answer store hoga.

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for i in range(1, n+1):

Loop 1 se n tak ek-ek number dega.

Agar n = 5 hai to:

i = 1
i = 2
i = 3
i = 4
i = 5

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fact = fact * i

Har baar current number (i) ko previous answer (fact) se multiply karte hain.

i	Calculation	fact
1	1 × 1	1
2	1 × 2	2
3	2 × 3	6
4	6 × 4	24
5	24 × 5	120

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return fact

Loop khatam hone ke baad final answer return kar deta hai.

Output:

120

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Easy Memory Trick

1. Start with fact = 1
2. Take numbers from 1 to n
3. Multiply each number with the previous answer
4. Return the final answer

Ek line mein yaad rakho:

Factorial program ka kaam hai 1 se n tak ke sabhi numbers ko multiply karke final answer return karna.