CODEWITHSUNDEEP
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Brett
Brett

Reputation: 183

Printing letters from a File 3 Letters at a Time in Python

I am trying to write a function that opens a filename, reads the contents of the file, and then prints the contents 3 letters at a time. Here is what I have tried:

def trigram_printer(filename):

    open_file = open(filename)
    copy = open_file
    three_letters = copy.read(4)


    for contents in copy:
        print(three_letters)

    open_file.close

Upvotes: 2

Views: 1081

Answers (2)

Malik Brahimi
Malik Brahimi

Reputation: 16711

copy simply points to open_file and your printing the letters for the number of lines in copy:

with open('test.txt') as open_file:
    data = open_file.read(3)

    while data != '':
        print(data) # print 3-gram
        data = open_file.read(3)

Just use a continuous loop to test if the file buffer is empty and print the data during the iteration.

Upvotes: 0

alexwlchan
alexwlchan

Reputation: 6098

There are several things I’d change about this code:

  • You never update the three_letters variable, which is why it prints the same thing repeatedly. You need to update the value of three_letters (by reading three more characters from the file) after you print it.
  • You copy the open_file object, when I’d just use it directly.
  • By doing .read(4), you print the contents 4 letters at a time, not 3.
  • You’re using the f = open(filename); ...; f.close() construction, rather than the more conventional with open(filename) as f; ....

With those thoughts in mind, here’s how I’d write your trigram printer:

def trigram_printer(filename):
    """Prints the contents of <filename>, three characters at a time."""
    with open(filename, 'r') as f:
        three_letters = f.read(3)

        while three_letters:
            print(three_letters)
            three_letters = f.read(3)

The key part is that every time three_letters gets printed, this function reads the next three characters from the file. When it runs out of characters, three_letters will be an empty string and the while loop will stop.

Upvotes: 3

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