Python - Read comma separated values from a text file, then output result to text file [closed]

Answer 1

Welcome to StackOverflow!

You have the right idea going, let's start by opening some files.

with open("text.txt", "r") as filestream:
    with open("answers.txt", "w") as filestreamtwo:

Here, we have opened two filestreams "text.txt" and "answers.txt".

Since we used "with", these filestreams will automatically close after the code that is whitespaced beneath them finishes running.

Now, let's run through the file "text.txt" line by line.

for line in filestream:

This will run a for loop and end at the end of the file.

Next, we need to change the input text into something we can work with, such as an array!

currentline = line.split(",")

Now, "currentline" contains all the integers listed in the first line of "text.txt".

Let's sum up these integers.

total = str(int(currentline[0]) + int(currentline[1]) + int(currentline [2])) + "\n"

We had to wrap the int function around each element in the "currentline" array. Otherwise, instead of adding the integers, we would be concatenating strings!

Afterwards, we add the carriage return, "\n" in order to make "answers.txt" clearer to understand.

filestreamtwo.write(total)

Now, we are writing to the file "answers.txt"... That's it! You're done!

Here's the code again:

with open("test.txt", "r") as filestream:
    with open("answers.txt", "w") as filestreamtwo:
        for line in filestream:
            currentline = line.split(",")
            total = str(int(currentline[0]) + int(currentline[1]) + int(currentline [2])) + "\n"
            filestreamtwo.write(total)

Answer 2

Wondering if the file has only comma separated values then why not save file as ".csv" format. If you can then:

You can always use a csv reader to read any CSV file as mentioned under the docs: http://docs.python.org/2/library/csv.html

Quick example for your scenario:

with open('test.csv','rb') as csvfile:
    csvreader = csv.reader(csvfile)
    output_fil = open('output.txt', 'ab')
    for row in csvreader:
        result = 0
        for elem in row:
            result = result + int(elem)
        print result
        output_fil.writelines(str(result))

Where text.csv would contain input like:

1,2,3
4,5,6
...

and output.txt shall contain:

6
15
..

Answer 3

For this task you may want to not work with files in your program directly, but work with standard input (input() or raw_input() in Python 2) and standard output (just print()).

Then you specify input and output file names during invocation of your script:

python script.py < file.txt > answer.txt

With this scheme you can have a program like this (Python 2.7):

while (True):
    try:
        x, y, z = [int(val) for val in raw_input().split(',')]
        print (x + y + z)
    except EOFError:
        pass

Answer 4

INFILE = "input.csv"
OUTFILE = "my.txt"

def row_sum(row, delim=","):
    try:
        return sum(int(i) for i in row.split(delim))
    except ValueError:
        return ""

with open(INFILE) as inf, open(OUTFILE, "w") as outf:
    outf.write("\n".join(str(row_sum(row)) for row in inf))

Answer 5

with open("file2.txt","w") as f:
    print >> f,"\n".join(map(lambda x:str(sum(int(y) for y in x.split(","))),open("file1.txt")))

Answer 6

You can do this in fewer lines, but I hope you find this solution readable and easy to understand:

out = file('answers.txt', 'w')
for line in file('file.txt', 'r'):
    s = 0
    for num in line.strip().split(','):
        s += int(num)
    out.write("%d\n" % s)