A function with 2 arguments:

def f(a,b): c = a * b return c print(f(2,3)) Output: 6

Recursive function:

def factorial(n): if n>1: return n*factorial(n-1) else: return n print(factorial(3)) Output: 6

Star argument means I don’t know how many arguments. The argument is stored as a tuple.

def total(*args): return(sum(args)) print(total(1,2,3)) Output: 6

def proper_case(a): return " ".join([word[0].upper() + word[1:] for word in a.split()]) print(proper_case("going to town")) Output: Going To Town

Lambda is a shortcut to create a function on the fly.

f = lambda a,b: a*b print(f(2,3)) Output: 6

Use map to pair a function to a list (to run the function to every element in the list)

Use filter to apply a condition to a list, to look for elements which satisfy that condition.

Use reduce to apply a function to a pair of values each time, repeatedly (reduce is in functools library)

# Using map and lambda to find words beginning with a L= ['Apple', 'Andy', 'Banana', 'Ben'] list(map(lambda x: 1 if x[0].lower() == 'a' else 0, L)) Output: [1, 1, 0, 0]

# Using map and lambda to produce cube numbers input_list = [1,2,3] list(map(lambda x: x**3, input_list)) Output: [1, 8, 27]

# Using map to pair 2 lists def v_add(x,y): return(x+y) list1 = [1,2,3] #Argument1 is a list list2 = (4,5,6) #Argument2 is a tuple print(list(map(v_add, list1, list2))) #We pass 2 arguments to map Output: [5, 7, 9]

# Using map to pair 2 lists L1 = ['P','O'] L2 = ['X','Y'] list(map(lambda x,y: x + ' ' + y, L1, L2)) Output: ['P X', 'O Y']

# Using filter to find the even numbers f = lambda x: x%2 == 0 L = [1,2,3,4,5,6] list(filter(f, L)) Output: [2, 4, 6] # Now using lambda list(filter(lambda x: x % 2 == 0, L)) Output: [2, 4, 6]

# Using filter to find the words that starts with a and ends with y L = ['Apple', 'Andy', 'Banana', 'Ben'] list(filter(lambda x: x[0].lower()=='a' and x[-1].lower()=='y', L)) Output: ['Andy']

# Using reduce to sum the input from functools import reduce def v_add(x,y): return(x+y) reduce(v_add, range(1,4)) Output: 6 # Now using lambda reduce(lambda x, y: x+y, range(1,4)) Output: 6

# Using reduce to find the largest number L = [22,45,32,20,87,94,30] def v_max(x,y): if x>y: return x else: return y #or v_max = lambda x,y: x if x>y else y reduce(v_max,L)

# Using reduce to concatenate letters L = ['A','B','C'] v_concat = lambda x,y: x+y reduce(v_concat, L) Output: 'ABC'

# Using reduce to calculate 1 x 2 x 3 x 4 x ... def f(x,y): return(x*y) n = 4 L = list(range(1,n+1)) print(1 if n == 0 else reduce(f,L)) Output: 24

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