Students¶

Save all functions into the same file named students.py.

To manage the class lists of a school year we use a dictionary dict where the key is a 3-tuple with the name and the two surnames of the student (str), and the associated value is the list of subjects in which they are enrolled. For example, the following dictionary:

dic = {('Joan', 'Rubio', 'Boix'): ['Programming', 'Physics', 'Calculus'],
       ('Anna', 'Pons', 'Adell'): ['Calculus', 'Programming']}

contains the student Joan Rubio Boix enrolled in Programming, Physics and Calculus and the student Anna Pons Adell enrolled in Programming and Calculus.

Write the modifier function add_student() that given a dictionary as that described, the name and two surnames of a new student (str), and a list with the subjects in which they are enrolled, modifies the dictionary by adding this new student. Examples:

>>> dic = {('Joan', 'Rubio', 'Boix'): ['Programming', 'Physics', 'Calculus']}
>>> add_student(dic, 'Anna', 'Pons', 'Adell', ['Programming', 'Calculus'])
>>> if dic != {('Joan', 'Rubio', 'Boix'): ['Programming', 'Physics', 'Calculus'],
... ('Anna', 'Pons', 'Adell'): ['Programming', 'Calculus']}:
...    print(dic)

Note

More tests are provided in test-students1.txt.

Write the function subject_student() that given a dictionary as that described, and the name and two surnames of a new student (str), returns the list of subjects in which that student is enrolled. If the student isn’t in the dictionary it returns an empty list. Examples:
```
>>> dic = {('Pol','Amber','Coll'):['PHY','PE','CHM'],
... ('Aina','Soler','Gil'):['PHY','PE','CHM','MTH']}
>>> subject_student(dic, 'Pol', 'Amber', 'Coll')
['PHY', 'PE', 'CHM']
```
Note

More tests are provided in test-students2.txt.
Write the function listed() that given a dictionary as that described and a subject (str), returns the list of all the students enrolled in this subject. In this list, a student must be represented with a string following this pattern: the first surname, a space, the second surname, a comma and a space, and the name. The list has to be sorted by the first surname. If no student is enrolled in the given subject, the function will return an empty list. Examples:
```
>>> dic = {('Pol','Amber','Coll'):['PHY','PE','CHM'],
... ('Aina','Soler','Gil'):['PHY','PE','CHM','MTH'],
... ('Joan','Rubio','Boix'):['PE','CHM','MTH', 'ENG'],
... ('Mar','Pou','Coll'):['PE','GE']}
>>> listed(dic, 'PHY')
['Amber Coll, Pol', 'Soler Gil, Aina']
>>> listed(dic, 'PR')
[]
```
Note

More tests are provided in test-students3.txt.

Write the function students_per_subject() that given a dictionary as that described, returns another dictionary where the key is the name of a subject, and its associate value is the number of students enrolled in this subject. Examples:

>>> dic = {('Pol','Amber','Coll'):['PHY','PE','CHM'],
... ('Aina','Soler','Gil'):['PHY','PE','CHM','MTH'],
... ('Joan','Rubio','Boix'):['PE','CHM','MTH', 'ENG'],
... ('Mar','Pou','Coll'):['PE','GE']}
>>> ds = students_per_subject(dic)
>>> if ds != {'PHY':2,'PE':4,'CHM':3,'MTH':2,'ENG':1,'GE':1}:
...     print(ds)

Note

More tests are provided in test-students4.txt.

Solution

A solution is provided in the students.py