Arrays / lists

Question 1

Add to end

Answer 1

list.append(value)

Question 2

Remove from start

Answer 2

list.pop(0)

Question 3

Remove from end

Answer 3

list.pop()

Question 4

Remove from middle of array

Answer 4

del my_list[startIndex:endIndex]

Deletes a portion of the list in place, removing all elements from startIndex up to but not including endIndex

Question 5

Length of list

Answer 5

len(my_list)

Question 6

Map elements in a list, square each element

Answer 6

new_list = list(map(lambda x: x * 2, original_list))

Question 7

Filter an array to create an array with elements over the value of 10

Answer 7

filtered_list = list(filter(lambda x: x > 10, original list))

Question 8

Create an array of squares from an existing list with list comprehension

Answer 8

squares = [x**2 for x in list_variable]

Question 9

Extend list with other list

Answer 9

list_variable.extend(another_list)

Question 10

Count the number of times an element is in a list

Answer 10

list_variable.count(element)

Question 11

Return the index of the first occurrence of an element, if not element not found value error

Answer 11

variable_list.index(element)

Question 12

Reverse list in place

Answer 12

list_variable.reverse()

Question 13

Check if element in list

Answer 13

if element in my_list:

if element not in my_list:

Question 14

Slice and assign values in list

Answer 14

variable_list[1:3] = [7, 8]

Question 15

Negative indexing, get last element

Answer 15

variable_list[-1]

Question 16

Join array to make string

Answer 16

‘-‘.join(arr)

Question 17

Sort list in place

Answer 17

my_list.sort()
my_list.sort(reverse=True)
my_list.sort(key=len)

Question 18

Sort and return new list

Answer 18

sorted_list = sorted(my_list)
sorted(my_list, reverse=True)

Question 19

Calculate sum of list

Answer 19

total_sum = sum(arr)

Question 20

Remove element from array

Answer 20

arr.remove(element)