How to use loop in Python to extract words (second and third in the line) from a txt file

Question

I have several txt files, that contain first and last name of the authors. Here are two examples among about thirty ( that do not contain the same number of authors ).

authors1.txt

AU  - Jordan, M. 
AU  - Thomson, J.J.  
AU  - Einstein, A.  
AU  - Tesla, N.

authors3.txt

AU  - Agassi, A.
AU  - Herbert, P.H.
AU  - Agut, R.B. 

I want to extract the last and first name of the authors for each file. Since I am a beginner in Python, I wrote a script (more or less suitable).

with open('authors3.txt', 'rb') as f:
    textfile_temp = f.read()

#o_author1 
o_author1 = textfile_temp.split('AU  - ')[1]
L_name1  = o_author1.split(",")[0]
F_name1  = o_author1.split(",")[1]
print(L_name1)
print(F_name1)

#o_author2 
o_author2 = textfile_temp.split('AU  - ')[2]
L_name2  = o_author2.split(",")[0]
F_name2  = o_author2.split(",")[1]
print(L_name2)
print(F_name2)

#o_author3 
o_author3 = textfile_temp.split('AU  - ')[3]
L_name3  = o_author3.split(",")[0]
F_name3  = o_author3.split(",")[1]
print(L_name3)
print(F_name3)

my result is:

Agassi
 A.

Herbert
 P.H.

Agut
 R.B.

My question: Is it possible to write a script with a loop, knowing that the files authors#.txt , don't each contain the same number of authors?

Answer 1

Using a simple for-loop

Demo:

authors_firstName = []
authors_lastName = []
with open(filename, "r") as infile:
    for i in infile.readlines():
        val = i.strip().split("-")[-1].strip().split(",")   #str.strip to remove any leading or trailing space, split by "-"
        authors_firstName.append(val[0])
        authors_lastName.append(val[1])
print(authors_firstName)
print(authors_lastName)

Output:

['Jordan', 'Thomson', 'Einstein', 'Tesla', 'Agassi', 'Herbert', 'Agut']
[' M.', ' J.J.', ' A.', ' N.', ' A.', ' P.H.', ' R.B.']

Answer 2

I suggest you read your file line by line, let's say,

with open('authors1.txt', 'rb') as f:
    lines = f.readlines()

# lines = ["AU - Jordan, M.", "AU - Thomson, J.J.", "AU - Einstein, A.", "AU  - Tesla, N."]

for line in lines:
    o_author1 = line.split('AU  - ')[1]
    L_name1  = o_author1.split(",")[0]
    F_name1  = o_author1.split(",")[1]
    print(L_name1)
    print(F_name1)

Jordan
 M.
Thomson
 J.J.
Einstein
 A.
Tesla
 N.

Answer 3

You can fetch the files in your current (or any other) directory by using os.listdir() or os.walk() . After you've obtained a list of author text files, you can simply loop through them with a simple for loop.

Hint: for-looping over a file object will yield you one line at a time , until it reaches end of the file - this is also memory efficient, as it only reads one line at a time to memory, instead of loading the entire file contents to your memory.

If you abstract your author name getting to a function, you can then simplify your code to something like this:

import os

def get_author(line):
    name = line.strip().split('AU  - ')[1]
    firstname, lastname = name.split(',')
    return firstname, lastname

if __name__ == '__main__':
    files = [f for f in os.listdir('.') if os.path.isfile(f)]
    # You probably want a more fancy way of detecting author files
    files = [f for f in files if f.startswith('authors') and f.endswith('.txt')]

    authors = []
    for file in files:
        with open(file, 'r') as fd:
            for line in fd:
                authors.append(get_author(line))
    print(authors)

authors at the end of the script will be a list containing tuples - each tuple consisting of the first and last name of your author.

Answer 4

I'm a bit rough on my Python, so I'll give you some pseudocode:

lines = file.ReadAll()

for line in lines
    parts = line.split("-,")
    print parts[1], parts[2]

And that's it. Read the entire file into a variable, iterate over each line and extract the parts.

Or, basically do what @Rakesh suggested =)