简单的python脚本。 输入和输出不匹配

Question

Short version: The number of lines in the input and output files are not equal. I don't understand why as I am not adding or subtracting any lines ie input file has 12327 lines but output only has 11903.

I can't seem to find any fault with my code. I was hoping someone with more experience could? Thank you.

Detailed version: I have a simple python script made up of 3 functions.

Function 1 takes a list of numbers from a .txt file (infile), converts all of them into floats, and changes any negative numbers to 0. It then adds them to a list (orginal list). Each element of this list is then printed to an output file. It also tells you the number of lines in the input file.

Function 2 essentially checks the number of lines in the output file.

Function 3 is just runs functions 1 and 2.

The input file has 12327 lines whilst the output file only has 11903.

I made another input file to test the script. This .txt input file has 10 lines a few of which are negative numbers. However the output file is completely empty.

I don't understand why the input and output number of lines are different? I have included the code below.

I would appreciate any advice. Thank you.

def thelist():  #FUNCTION 1
    original_list = []
    for line in infile:
        newline = float(line)
        if newline < 0:
            newline = 0
        original_list.append(newline)
    print('The input file has', len(original_list), 'lines.')
    for element in original_list:
        print(element, file = outfile)

def outfilelinenumber():    #FUNCTION 2
    outfile = open('outfile.txt')
    improved_list = []
    for line in outfile:
        improved_list.append(line)
    if not improved_list:
        print('Output file is empty.')
    else:
        print('The output file has', len(improved_list), 'lines.')

def main(): #FUNCTION 3
    thelist()
    outfilelinenumber()
    print('\n', '*** Finished ***')


infile = open('infile.txt')
outfile = open('outfile.txt', 'w')

main()

Answer 1

One problem is that you never close your output file, so nothing is properly sent to it. You need to take care of your files: if you open it, close it properly. You also do not close your input file, though you do not see the problems that can result from that.

Replace your function with

def thelist():  #FUNCTION 1
    original_list = []
    for line in infile:
        newline = float(line)
        if newline < 0:
            newline = 0
        original_list.append(newline)
    print('The input file has', len(original_list), 'lines.')
    for element in original_list:
        print(element, file = outfile)
    infile.close()
    outfile.close()

Note the two close functions at the end. This takes care of your problem in my tests, though you do have other problems with your file handling that could cause problems. I suggest you look at the tutorial on file handling to learn better file-handling.

Answer 2

I can see some lines are not fully pushed to outfile.txt by the time the second method reads outfile, and finds it empty. This is because of the write operation not getting completed. As suggested in the previous answer by Rory, it is suggested to close the files after use for proper file handling. Even using flush() to complete any pending write operations will help here.

Please use below main() for proper results.

 def main(): #FUNCTION 3
    thelist()
    infile.flush()
    outfile.flush()
    outfilelinenumber()
    infile.flush()
    outfile.flush()
    print('\n', '*** Finished ***')

Using this the output was:

 The input file has 13 lines.
 The output file has 13 lines.

  *** Finished ***