Answer to Question #105231 in Python for Joe

Question

Provide your own examples of the following using Python lists. Create your own examples. Do not copy them from another source.

Nested lists
The “*” operator
List slices
The “+=” operator
A list filter
A list operation that is legal but does the "wrong" thing, not what the programmer expects
Provide the Python code and output for your program and all your examples.

Answer 1

Nested lists:

list_one = [[ 1, 2, 3, 4] , [ "H", "u", "n", "t", "e", "r"] , [ 23, 34, 11]]

The “*” operator:

def func (*x):

   return   list(x)

print(func(7,5,3)) #[7, 5, 3]

list_one = [ 1, 2, 3, 4]

print(list_one*2) #[1, 2, 3, 4, 1, 2, 3, 4]

List slices:

list_one = [ 1, 5 ,6, 7, 9]

list_two = list_one[1:4] #[5, 6, 7]

The “+=” operator:

list_one = [ 1, 5 ,6, 7, 9]

for i in list_one:

   i += 1

   print(i, end = " ") #2 6 7 8 10

A list filter :

list_one = [ 1, 5 ,6, 7, 9]

list_two = filter(lambda x: x % 2 == 0, list_one)

print(list(list_two)) #[6]

A list operation that is legal but does the "wrong" thing, not what the programmer expects:

def func(x, list_one=[]):

   list_one.append(x)

   print (list_one)

func(3)

func(4)

func(5) #we expect [3][4][5] 

#but have

[3] [3, 4] [3, 4, 5