python - pass single quote as value if the value is empty or null

Question

I have a input file like below and i am reading the file and checking the length of the file and below and want to check if arg_list[3] is null or empty and then pass '' as value to arg_list[3].

                                  1|2|3| |5
                                  

The code is below:

                                  f=open(input,'r')
                                  for line in f:
                                      arg_list=line.split('|')
                                      if len(arg_list) == 5:
                                          a=(arg_list[0].strip())
                                          b=(arg_list[1].strip())
                                          c=(arg_list[2].strip())
                                          d=(arg_list[3].strip())
                                          e=(arg_list[4].strip())
                                          w=open(output,'w')
                                          c.write("arg1=%s\n" % (a))
                                          c.write("arg2=%s\n" % (b))
                                          c.write("arg3=%s\n" % (c))
                                          c.write("arg4=%s\n" % (d))
                                          c.write("arg5=%s\n" % (e))
                                      f.close()
                

expected output (output) is as below

                                       arg1=1
                                       arg2=2
                                       arg3=3
                                       arg4=''
                                       arg5=5

Any ideas are appreciated

Answer 1

You can use {!r} in str.format to obtain your result:

If a1.txt contains:

                              1|2|3| |5

then:

with open('a1.txt', 'r') as f_in, open('a2.txt', 'w') as f_out:

    for line in f_in:
        if line.strip() == '':
            continue

        s = map(lambda x: '' if x.strip()=='' else int(x), s.split('|'))

        for i, v in enumerate(s, 1):
            print('arg{}={!r}'.format(i, v), file=f_out)

creates a2.txt with content:

arg1=1
arg2=2
arg3=3
arg4=''
arg5=5