Question

Python Question?

Write a function called reverse(user_list, num = -1) that takes a list and a number as parameters. The function returns a copy of the list with the first number of items reversed.

Conditions:

The number parameter must be a default argument.
-      If the default argument for number is given in the function call, only the first number of items are reversed.
-      If the default argument for number is not provided in the function call, then the entire list is reversed.

Check for the number value exceeding the list bounds (i.e. is greater than the length of the list).
-    If the number value exceeds the list bounds, then make the number value the length of the list.
-    If the number value entered is less than two, then return a copy of the list with no items reversed.

Must use a loop(s) in your solution.

Make use of the list_name.append(item) method in order to build the new list.

Must not use built-in functions (other than the range() function), slice expressions, list methods (other than the append() method) or string methods in your solution.

user_list1 = ['e', 'd', 'o', 'm']

user_list2 = ['l', 'o', 'w', 'b', 'e', 'd']

new_list = list_function.reverse(user_list1, 4)

print(new_list)

new_list = reverse(user_list2, 3)

print(new_list

new_list = reverse(userlist2, 2)

print(new_list)

new_list = reverse(user_list1)

print(new_list)

Answer 1

Here is the completed code for this problem. Comments are included, go through it, learn how things work and let me know if you have any doubts or if you need anything to change. If you are satisfied with the solution, please rate the answer. Thanks

Note: Please maintain proper code spacing (indentation), just copy the code part and paste it in your compiler/IDE directly, no modifications required. Assuming we can also use len() method (not mentioned) to find the length of list. If not, let me know, I’ll update the answer.

#code

#required method
def reverse(user_list, num = -1):
    #creating an empty list
    new_list=[]
    #checking if num is -1 (default argument; I suggest using None value as default which makes more
    # sense when the argument is not provided)
    if num==-1:
        #looping in reverse order, from last index to first
        #assuming we can use len() method to find list length, if not, let me know
        for i in range(len(user_list)-1,-1,-1):
            #appending element at index i to new_list
            new_list.append(user_list[i])
        #returning new list
        return new_list
    else:
        #if num exceeds length of user_list, setting length of user_list as num
        if num>len(user_list):
            num=len(user_list)
        #if num is less than 2, setting 0 as num
        elif num<2:
            num=0
        #looping down from num-1 to 0
        for i in range(num - 1, -1, -1):
            #adding element at index i to new_list
            new_list.append(user_list[i])
        #adding remaining elements in original order
        for i in range(num,len(user_list)):
            new_list.append(user_list[i])
        #returning new_list
        return new_list


#testing
user_list1 = ['e', 'd', 'o', 'm']
user_list2 = ['l', 'o', 'w', 'b', 'e', 'd']
new_list = reverse(user_list1, 4) 
print(new_list) # ['m', 'o', 'd', 'e']
new_list = reverse(user_list2, 3)
print(new_list) # ['w', 'o', 'l', 'b', 'e', 'd']
new_list = reverse(user_list2, 2)
print(new_list) # ['o', 'l', 'w', 'b', 'e', 'd']
new_list = reverse(user_list1)
print(new_list) # ['m', 'o', 'd', 'e']