Reading lines from a txt file and create a dictionary where values are list of tuples

Question

student.txt:

Akçam   Su Tilsim       PSYC 3.9
Aksel   Eda         POLS 2.78
Alpaydin Dilay          ECON 1.2
Atil    Turgut Uluç     IR 2.1
Deveci  Yasemin     PSYC 2.9
Erserçe Yasemin     POLS 3.0
Gülle   Halil       POLS 2.7
Gündogdu Ata Alp    ECON 4.0
Gungor  Muhammed Yasin  POLS 3.1
Hammoud  Rawan      IR 1.7
Has Atakan      POLS 1.97
Ince    Kemal Kahriman  IR 2.0
Kaptan  Deniz       IR 3.5
Kestir  Bengisu     IR 3.8
Koca    Aysu        ECON 2.5
Kolayli Sena Göksu  IR 2.8
Kumman  Gizem       PSYC 2.9
Madenoglu Zeynep    PSYC 3.1
Naghiyeva Gulustan  IR 3.8
Ok  Arda Mert   IR 3.2
Var Berna       ECON 2.9
Yeltekin Sude       PSYC 1.2

Hello, I want to write a function, which reads the information about each student in the file into a dictionary where the keys are the departments, and the values are a list of students in the given department (list of tuples). The information about each student is stored in a tuple containing (surname, GPA). Students in the file may have more than one name but only the surname and gpa will be stored. The function should return the dictionary. (Surnames are the first words at each line.)

This is what I tried:

def read_student(ifile):
    D={}
    f1=open(ifile,'r')
    for line in f1:
        tab=line.find('\t')
        space=line.rfind(' ')
        rtab=line.rfind('\t')
        student_surname=line[0:tab]
        gpa=line[space+1:]
        department=line[rtab+1:space]
        
        if department not in D:
            D[department]=[(student_surname,gpa)]
        else:
            D[department].append((student_surname,gpa))
    f1.close()
    return D
print(read_student('student.txt'))

I think the main problem is that there is a sort of disorder because sometimes tab comes after words and sometimes a space comes after words, so I dont know how to use find function properly in this case.

Answer 1

see below - you will have to take care of the surname but rest of the details in the question were handled

from collections import defaultdict

data = defaultdict(list)
with open('data.txt', encoding="utf-8") as f:
    lines = [l.strip() for l in f.readlines()]
    for line in lines:
        first_space_idx = line.rfind(' ')
        sec_space_idx = line.rfind(' ', 0,first_space_idx - 1)
        grade = line[first_space_idx+1:]
        dep = line[sec_space_idx:first_space_idx]
        student = line[:sec_space_idx].strip()
        data[dep].append((student, grade))
for dep, students in data.items():
    print(f'{dep} --> {students}')

output

 PSYC --> [('Akçam   Su Tilsim', '3.9'), ('Deveci  Yasemin', '2.9'), ('Kumman  Gizem', '2.9'), ('Madenoglu Zeynep', '3.1'), ('Yeltekin Sude', '1.2')]
 POLS --> [('Aksel   Eda', '2.78'), ('Erserçe Yasemin', '3.0'), ('Gülle   Halil', '2.7'), ('Gungor  Muhammed Yasin', '3.1'), ('Has Atakan', '1.97')]
 ECON --> [('Alpaydin Dilay', '1.2'), ('Gündogdu Ata Alp', '4.0'), ('Koca    Aysu', '2.5'), ('Var Berna', '2.9')]
 IR --> [('Atil    Turgut Uluç', '2.1'), ('Hammoud  Rawan', '1.7'), ('Ince    Kemal Kahriman', '2.0'), ('Kaptan  Deniz', '3.5'), ('Kestir  Bengisu', '3.8'), ('Kolayli Sena Göksu', '2.8'), ('Naghiyeva Gulustan', '3.8'), ('Ok  Arda Mert', '3.2')]

Answer 2

Why mess with rfind and find when you can simply split ?

def read_student(ifile):
    D = {}
    f1 = open(ifile,'r')
    for line in f1:
        cols = line.split() # Splits at one or more whitespace
        surname = cols[0].strip()
        department = cols[-2].strip() # Because you know the last-but-one is dept
        gpa = float(cols[-1].strip()) # Because you know the last one is GPA
        fname = ' '.join(cols[1:-2]).strip() 
        # cols[1:-2] gives you everything starting at col 1 up to but excluding the second-last. 
        # Then you join these with spaces.


        if department not in D:
            D[department] = [(surname, gpa)]
        else:
            D[department].append((surname, gpa))

    f1.close()
    return D

If you know that your columns are separated by \\t always, you can do cols = line.split('\\t') instead. Then you have the students' fname in the second column, the department in the third, and the GPA in the fourth.

A couple of suggestions:

1. You can use defaultdict to avoid checking if department not in D every time
2. You can use with to manage reading the file so you don't have to worry about f1.close() . This is the preferred way to read files in Python.

Answer 3

You can use split(' ', 1) to extract surname. It gives list with two elements. first one is surname. Then again split the second elements to get the using rsplit(' ', 1) . It again gives list with two element first one is name and dept and second one is gpa. Again split second element to get department.

def read_student(ifile):
    d = {}
    with open(ifile) as fp:
      for line in fp:
          fname, data = line.strip().split(' ', 1)
          data, gpa = data.rsplit(' ', 1)
          dept = data.split()[-1]
          d.setdefault(dept, []).append((fname, gpa))
      return d

print(read_student('student.txt'))

Output:

{'ECON': [('Alpaydin', '1.2'),
          ('Gündogdu', '4.0'),
          ('Koca', '2.5'),
          ('Var', '2.9')],
 'IR': [('Atil', '2.1'),
        ('Hammoud', '1.7'),
        ('Ince', '2.0'),
        ('Kaptan', '3.5'),
        ('Kestir', '3.8'),
        ('Kolayli', '2.8'),
        ('Naghiyeva', '3.8'),
        ('Ok', '3.2')],
 'POLS': [('Aksel', '2.78'),
          ('Erserçe', '3.0'),
          ('Gülle', '2.7'),
          ('Gungor', '3.1'),
          ('Has', '1.97')],
 'PSYC': [('Akçam', '3.9'),
          ('Deveci', '2.9'),
          ('Kumman', '2.9'),
          ('Madenoglu', '3.1'),
          ('Yeltekin', '1.2')]}

Answer 4

This solution makes use of itemgetter to simplify the getting of variables: surname, dept. and gpa

from operator import itemgetter
d = dict()

with open('f0.txt', 'r') as f:
    for line in f:
        name, dept, gpa = itemgetter(0, -2, -1)(line.split())
        d.setdefault(dept, []).append((name, gpa))