collections.namedtuple()

Basically, namedtuples are easy to create, lightweight object types.

They turn tuples into convenient containers for simple tasks.

With namedtuples, you don’t have to use integer indices for accessing members of a tuple.

Example

Code 01

from collections import namedtuple
Point = namedtuple('Point','x,y')
pt1 = Point(1,2)
pt2 = Point(3,4)
dot_product = ( pt1.x * pt2.x ) +( pt1.y * pt2.y )
print dot_product
11

Code 02

from collections import namedtuple
Car = namedtuple('Car','Price Mileage Colour Class')
xyz = Car(Price = 100000, Mileage = 30, Colour = 'Cyan', Class = 'Y')
print xyz
Car(Price=100000, Mileage=30, Colour='Cyan', Class='Y')
print xyz.Class
Y

Task

Dr. John Wesley has a spreadsheet containing a list of student's $\textit{IDs}$, $marks$, $class$ and $name$.

Your task is to help Dr. Wesley calculate the average marks of the students.

$\textit{Average}=\dfrac{\textit{Sum of all marks}}{\textit{Total students}}$

Note:

1. Columns can be in any order. IDs, marks, class and name can be written in any order in the spreadsheet.

2. Column names are ID, MARKS, CLASS and NAME. (The spelling and case type of these names won't change.)

Input Format

The first line contains an integer $N$, the total number of students.

The second line contains the names of the columns in any order.

The next $N$ lines contains the $marks$, $\textit{IDs}$, $name$ and $class$, under their respective column names.

Constraints

$0<N\leq100$

Output Format

Print the average marks of the list corrected to 2 decimal places.

Sample Input

TESTCASE 01

5
ID MARKS NAME CLASS
1 97 Raymond 7
2 50 Steven 4
3 91 Adrian 9
4 72 Stewart 5
5 80 Peter 6

TESTCASE 02

5
MARKS CLASS NAME ID
92 2 Calum 1
82 5 Scott 2
94 2 Jason 3
55 8 Glenn 4
82 2 Fergus 5

Sample Output

TESTCASE 01

78.00

TESTCASE 02

81.00

Explanation

TESTCASE 01

Average = $(97+50+91+72+80)/5$

Can you solve this challenge in 4 lines of code or less?

NOTE: There is no penalty for solutions that are correct but have more than 4 lines.

见题面

见题面