2.2 List Operations

1. .count() returns the frequency of an item. my_list.count('Monday')
2. .sort() sorts the list my_list.sort() in assending order
3. .reverse() reverses the order my_list.reverse() in decending order
4. min() returns the smallest item min(my_list)
5. max() returns the largest item max(my_list)
6. sum() returns the sum of the items sum(my_list)
7. len() returns the number of items on the list (size) len(my_list)

Example: what is the frequency count for the element "Monday" for the list x = ['Monday', 'Tuesday', 'Wednesday', 'Monday', 4, 5, 6, 4, 4, 7.0]?

x = ['Monday', 'Tuesday', 'Wednesday', 'Monday', 4, 5, 6, 4, 4, 7.0]
x.count('Monday')

2

Example: Sort the list y = [10,14,20,15]. Print the sorted list.

y = [10,14,20,15]
y.sort()
y

[10, 14, 15, 20]

Example: Use the sorted list y from above to reverse the order.

y = [10,14,20,15]
y.reverse()   # revers order
y

[15, 20, 14, 10]

Example: Use the list y = [10,14,20,15] above to find the minimum item of the list.

y = [10,14,20,15]
min(y)

10

Example: Use the list y = [10,14,20,15] above to find the maximum item of the list.

y = [10,14,20,15]
max(y)

20

Example: Use the list y = [10,14,20,15] above to find the sum of all items in the list.

y = [10,14,20,15]
sum(y)

59

Example: Use the list y = [10,14,20,15] above to find the length of the list. That is, how many items are there in the list?

y = [10,14,20,15]
len(y)    

4

Example: Write a Python program that displays the sum, minimum, maximum and length of the values of the elements in a given list, x=[1,2,3,4,5,6,7,8,9]

x=[1,2,3,4,5,6,7,8,9]

print('the sum is:',sum(x))
print('the min is:',min(x))
print('the max is:',max(x))
print('the length is:',len(x))

the sum is: 45
the min is: 1
the max is: 9
the length is: 9

Adapted from Python for Introductory Statistics, by Simon Aman (Truman College, City Colleges of Chicago), licensed under CC BY 4.0. Changes were made: reformatted as an accessible XYZ web edition with live in-browser code cells. License: CC-BY-4.0.