Python Course – 8. Files

We program so that a machine manages data for us, and the way we want it to. Files let us store as much data as we want: some files with information before it is processed and others with the information after it has been processed; that is why they will be one of the main inputs and outputs of our programs.

Theory

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8.1- Files and Directories

An operating system (Windows, Linux, Mac, Android, etc.) manages data with files, and these are organized in directory structures. Knowing how to manage files and directories is a crucial point when working with them.

8.2- Paths

A path is the route to follow through the directories to reach one or more files. With the Path method, it will be very easy and practical to work with as many files as we want.

Exercises

Exercise 8.1-crear_fichero_y_leer_fichero.py

Using Python code, create a directory in a location on your computer and a file inside it.

Inside the file, write five lines of random numbers from 1 to 10 (Part 1).

Then read that file and print each line to the screen.

Next, add a couple of lines of text at the end of the file (Part 2).

And read the file again.

Exercise 8.2-futbolistas.py

Given the file “futbolistas.txt”, in which each line contains the data of a soccer player, you are asked to:

1. Implement a function called “file_to_list(file_dir)” that, given the path of the file futbolista.txt, returns a
   list in which each element corresponds to a line of the file; that is, each element represents the data of one player.
2. Implement a function called “get_top_goals_players(list_players, top_n)” that, given the list of players,
   returns in another list the “top_n” top-scoring players.
3. Implement a function called “get_players_by_team(list_players, team)” that, given the list of players, returns
   in another list all the players who have played for the team passed as a parameter (team), sorted in descending order by the number of minutes they have played.
4. Implement a function called “write_list_to_file(list_to_write, file_dir)” that, given the list passed as a
   parameter (list_to_write), writes each element of the list on its own line in the file passed as the parameter “file_dir”.
5. Write the lists created in points b and c to a file, using the function implemented in point d.

In the futbolistas.txt file, each line contains the data of a soccer player, and the data are separated by the separator “::”. The data at each position are the following:

1	id	14	PartidosCompletos	27	Numligas
2	Apodo	15	PartidosSuplente	28	NumCopasDelRey
3	Nombre	16	PartidosSustituidos	29	NumSuperCopas
4	FechaNacimiento	17	partidosPorTemporadas	30	NumChampions
5	LugarNacimiento	18	PorcentajePartidos	31	NumUEFAs
6	Pais	19	MinutosJugados	32	NumEuropaLeagues
7	Altura	20	MinutoPorPartido	33	NumSuperCopasEuropa
8	Peso	21	Goles	34	NumMundialesClubes
9	Demarcacion	22	TarjetasAmarillas	35	NumIntercontinentales
10	NumTemporadas	23	TarjetasRojas	36	NumMundiales
11	NumEquipos	24	PartidosSeleccionEspaniola	37	Numeurocopas
12	PartidosJugados	25	GolesSeleccionEspaniola	38	ValorMercado
13	PartidosTitular	26	Equipos