Writing Lines to a Different File

Question

I am reading content from a file (scores.txt) and I have formatted the data that I need from it and I would like to write those lines to a new file. The new file I will be writing to is top_scores.txt. Below is the code for the desired output. I am just not entirely sure how to print to the file.

infile = open('scores.txt', 'r')
lineList = sorted(infile.readlines())

for lines in lineList:
    newLine = lines.replace('\n', '')
    splitLines = newLine.split(',')
    studentNames = splitLines[0]
    studentScores = splitLines[1:]
    studentsList = []
    for i in studentScores:
        studentsList.append(int(i))
    topScore = max(studentsList)
    print(studentNames.capitalize() + ': ', studentsList, 'max score =', int(topScore))

Sample from scores.txt:

Pmas,95,72,77,84,86,81,74,\\n

Sample for desired input for new file:

Pmas: [95,72,77,84,86,81,74], max score = 95\\n

Answer 1

"(...) the variables I have defined to hold the data I need, are not defined (...)"

Maybe that's caused by lines like these:

for i in studentScores:
    float(i)

float(i) doesn't convert the value of i in a "lasting" way unless you assign a variable to it; eg do score = float(i) or whatever you want to call it. You can then work with score which is now a floating point number.

When writing to files, like in the line below, you have to write a single string at a time. When you place a comma between the values, they won't be combined into a single string so python will most likely fail with a TypeError: function takes exactly 1 argument (x given) .

infile2.write(studentNames.capitalize() + ': ', studentsList, 'top score =', int(topScore))

If studentNames and studentsList are list s and int(topScore) is an integer, none of the variables can be written to a file as is. You will need to select individual strings from your list s (eg studentNames[0] ) or use " ".join(name_of_your_list) to combine all elements into a single string. int(topScore) will have to be converted to a string via str(topScore) .

"I am just not entirely sure how to print to the file."

The easiest way to handle file reading/writing is via with open(filename, mode) handle: . Eg:

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

Just some observations that'll explain at least some of the errors you're probably getting...

Answer 2

To write to a file just use :

file = open("top_score.txt", "a")
str=', '.join(str(x) for x in studentsList)
file.write(studentNames.capitalize() +'\t'+str+'\t'+(topScore))
file.close();

Answer 3

Here is a correct way to achieve what you want :

with open("scores.txt", 'r') as infile, open("top_score.txt", 'w') as outfile, open("top_score2.txt", '\
w') as outfile2:
    lineList = sorted(infile.readlines())
    for lines in lineList:
        newLine = lines.replace('\n', '')
        splitLines = newLine.split(',')
        studentNames = splitLines[0]
        studentScores = splitLines[1:]
        studentsList = []
        for i in studentScores:
            if i == '':
                break
            studentsList.append(int(i))
        topScore = max(studentsList)
        result = "%s: %s,max score = %d" % (studentNames.capitalize(),
                                            str(studentsList),
                                            max(studentsList))
        print(result)
        print(result, file = outfile)
        outfile2.write(result + "\n")

Note that I used two ways to print the result :

• print() file parameter.
• file.write() method.

Also note that I used a with statement like jDo suggested.

This way, it permits to open a file and to automatically close it when exiting the block.

EDIT :

Here is a version that is even shorter :

with open("scores.txt", 'r') as infile, open("top_score.txt", 'w') as outfile, open("top_score2.txt", 'w') as outfile2:
    lineList = sorted(infile.readlines())
    for lines in lineList:
        lines = lines.replace('\n', '').split(',')
        studentScores = lines[1:-1]
        studentsList = [int(i) for i in studentScores]
        result = "%s: %s,max score = %d" % (lines[0].capitalize(),
                                            str(studentsList),
                                            max(studentsList))
        print(result)
        print(result, file = outfile)
        outfile2.write(result + "\n")