Pandas: Create a DataFrame using a for loop

# Import library
import pandas as pd
import random 
import string

# Function - 1: Square a number
def sq(m):
    return m**2

# Function - 2: Create a random key
def rand(nkey):
    rl = string.ascii_letters # random alphabet
    rd = string.digits # random digit
    return ''.join(random.choices(rl + rd, k=nkey))

# List
x = [1,2,3,4,5]
nkey = 15 # key length

# Create DataFrame using for loop and functions
df = pd.DataFrame({
    'num': x,
    'num_sq': [i**2 for i in x],
    'num_sq_func': [sq(i) for i in x],
    'random_key': [rand(nkey) for _ in range(len(x))]
    
})

# Output
print(df)