Only to be submitted if you did not obtain an exemption for the group project

MatchAnalysis Part 4 — Saving and Loading

In this part you will add functionality to save the PassGraph to a .txt file and to reconstruct it from such a file.

File format

Two sections: [PLAYERS] and [PASSES].

[PLAYERS]
<name>;<number>
<name>;<number>
[PASSES]
<sender_name> -> <receiver_name> : <nr_of_times>

Rules

• Comment lines start with # and are ignored.
• Empty lines are ignored.
• Duplicate passes → weights are summed.
• Invalid input → raise ValueError.

Example file

Team: Red Devils
[PLAYERS]
Eden Hazard;10
Moussa Dembele;19
Jan Vertonghen;5
Romelu Lukaku;9
[PASSES]
Eden Hazard -> Moussa Dembele : 7
Eden Hazard -> Romelu Lukaku : 2
Jan Vertonghen -> Romelu Lukaku : 1

Tasks (5 points)

Extend your PassGraph class with:

1) Basic operations (1 point)

• Method players(self)
  • Return a copy of the player list.
• Method passes(self)
  • Return all passes in the graph.

2) Constructor with path parameter (2 points)

Signature
The constructor accepts an optional argument path (string).

Behavior

• Without path, the constructor creates an empty graph.
• With path, the constructor immediately reads the text file and populates the graph.

Reading requirements

• Support comment lines (# ...) and empty lines.
• Recognize the sections [PLAYERS] and [PASSES]; any other section → ValueError with a short message.
• In [PLAYERS]: each line is name;number. Strip spaces around fields. number must be convertible to int. Add players first using add_player.
• In [PASSES]: each line is sender_name -> receiver_name : nr. Strip spaces around fields. nr must be a positive integer. Add passes using add_pass. If the same pass appears multiple times, the total must be correct.
• If a pass refers to a player not listed in [PLAYERS] → raise ValueError.

3) save_to_txt(self, path) (1 point)

Save the entire graph in exactly the file format described above.

Requirements

• Overwrite the target file if it already exists.
• Write [PLAYERS] first (one player per line in the form name;number).
• Then write [PASSES] (one pass per line in the form sender -> receiver : nr).
• The order is up to you (e.g. players alphabetically, passes per sender), but be consistent.

4) Testing (1 point)

Write a test script that:

• Builds a PassGraph (at least 4 players and 4 passes, with one pass added multiple times).
• Calls save_to_txt("team.txt").
• Reads the graph back with the constructor:
  ```python g2 = PassGraph(“team.txt”)