Read and modify file to a copy in Python

Question

I am looking for a way to copy a txt file and modify it so that every sentence begins a new line.

I am very new to programming in Python and would like some help explaining how can I do this.

For example,

First sentence. Second. Third.

Should be

First sentence.

Second.

Third.

This is what I have so far:

f=open('a.txt')  
f1=open('b.txt','a')
with open('a.txt', 'r') as file:
    string = file.read().replace('.', '.\n')
with open('b.txt', 'w') as b:
    b.write(string)
f1.close()
f.close()

Answer 1

This can be done using the replace method for strings. https://www.geeksforgeeks.org/python-string-replace/

Basically, you just tell it what you are wanting to replace (in this case punctuation at the end of a sentence) and what to replace it with (a new line).

    string = 'First sentence. Second. Third.'
    print(string)

    string = string.replace(". ", ".\n")
    print(string)

Consider using replace for ? and ! as well.

As for writing to the result file, after you have the modified text in your string variable:

with open("output_file.txt", "w") as output_file:
    output_file.write(string)

The "w" parameter on open allows you to write to the file.

Answer 2

text = "First sentence. Second. Third."
text = text.split(". ")
for x in range(0,len(text)):
    if "." in text[x]:
        text[x] = text[x][:-1]
    print(text[x]+".")

Answer 3

You first need to define what is a sentence for you. On this case, a sentence is separeted by '.', so you just need to imput:

a = "First sentence. Second. Third." print(a.replace(". ", ".\n"))

But if you will consider others caracteres, like '!', '?' and ';', you will also put those options too.

All code:

f = open("demofile.txt", "r")
print(f.read())

a = f.read()
print(a.replace(". ", ".\n"))

f = open("demofile2.txt", "a")
f.write(a.replace(". ", ".\n"))