Move a character left or right in a file.

[woooee]

You can just swap the two values instead of iterating over the string.

    line='100000040000001'
    pos = line.index('4')

    ## move to the left
    line_as_list=list(line)
    if pos > 0:
        new_pos=pos - 1  ## move to right= pos + 1
        save_this=line_as_list[new_pos]
        line_as_list[new_pos]='4'
        line_as_list[pos]=save_this

    ## print one above the other for easy comparison
    print(line)
    print("".join(line_as_list))