While working at the command-line, I came up with the idea for this little Python utility which displays a ruler on the console. You can use this program's output as a ruler, to find the character positions and lengths of parts of your own program's output on the line, or to measure the lengths of fields in fixed-length or variable-length records in a text file or CSV file which you need to process via your program. And of course, your program can be in any language, not just Python.
Note: the program is written assuming a console width of 80 characters. You can change some of the values in it if you need it to work with a console of a different width.
I've called it ruler.py. Here is the code for it:
""" # ruler.py - A program to display a ruler on the command line. Copyright 2014 Vasudev Ram - http://www.dancingbison.com Program to display a line on the command-line screen. The line consists of repeated occurrences of the characters: 0123456789, concatenated. Purpose: By running this program, you can use its output as a ruler, to find the position of your own program's output on the line, or to measure the lengths of fields in fixed- or variable-length records in a text file, fields in CSV files, etc. """ import sys def ruler(units="0123456789", repeats=8, fives=True): for i in range(repeats): if i < repeats - 1: if fives: sys.stdout.write(str(i) + (" " * 4) + "5" + (" " * 4)) else: sys.stdout.write(str(i) + (" " * 9)) else: if fives: sys.stdout.write(str(i) + (" " * 4) + "5" + (" " * 3)) else: sys.stdout.write(str(i) + (" " * 8)) sys.stdout.write("\n") #sys.stdout.write(units * repeats + "\n") sys.stdout.write(units * repeats) sys.stdout.flush() def main(): ruler() if __name__ == "__main__": main() # EOFAnd here is its output:
$ python ruler.py 0 5 1 5 2 5 3 5 4 5 5 5 6 5 7 5 01234567890123456789012345678901234567890123456789012345678901234567890123456789 $And the output from this call to ruler():
0 1 2 3 4 5 6 7 01234567890123456789012345678901234567890123456789012345678901234567890123456789I've parameterized the values it uses, to some extent, so you can customize them. You can also import the file ruler.py as a module and call its ruler() function in your own Python program. The code for doing that is as simple as:
# test_ruler.py from ruler import ruler ruler()The Wikipedia article on rulers is interesting. So is the Golomb ruler. And here is a rolling ruler: - Vasudev Ram - Dancing Bison Enterprises Contact Page