Best sparkling utility

David Lowe
434 Tenney Drive
Rogue River, OR
97537
j.david.lowe@gmail.com
http://www.pootpoot.net/

Judges' comments:

To build:

make dlowe

To run:

./dlowe [numbers...]

Try:

./dlowe 0 1 2 3 4 5 6 7
./dlowe 16 32 64 128

echo sparkline of file sizes: `wc -c * | awk '{print $1}' | xargs ./dlowe`

./dlowe 0

Selected Judges Remarks:

We liked how this entry used Unicode, specifically UTF-8, in a somewhat obfuscated way.

Also, why doesn’t it crash, and produces a correct output when called with one argument or when all arguments are equal?

For extra fun, compile and run

#include <stdio.h>
int main() {
    printf("%d %d %d\n", (int)(-1.0/0.0), (int)(0.0/0.0), (int)(1.0/0.0));
}

with gcc and clang.

With GCC (4.7.2), we get

-2147483648 -2147483648 -2147483648

and with clang (3.3), we get

-2147483648 0 2147483647

Which one is correct? :)

Author’s comments:

sparkl

A tiny implementation of command-line ‘sparkline’ data visualization.

Synopsis

$ sparkl 0 1 2 3 4 5 6 7
▁▂▃▄▅▆▇▉

$ echo sparkline of file lengths: `wc -c * | awk '{print $1}' | xargs sparkl`
sparkline of file sizes: ▁▁▁▃▃▂▁▂▁▁▉

Description

This is a handy little tool for visualizing numeric series from the command-line, using ‘sparklines’. Pass it a numeric series as arguments, and sparkl will display a sparkline graph, which you can use to very quickly get a sense of the shape of your data.

Limitations

Crashes with 0 arguments. It’d be trivial to fix, but adds a few bytes to the code.
Produces bogus graphs when given > about 5000 arguments.
Only works if your terminal is utf-8 and your font supports the 8 glyphs used.
Produces a few harmless compiler warnings.

Obfuscation

The code is very terse. I was torn between submitting this version, and a one-line version compressed using a couple more -D flags.

Hand-rolled utf-8 sequence, magic numbers (what’s that 7 for?), meaningless variable names, reused variables, and so on.

Acknowledgements

Edward Tufte invented sparklines (among other things.) Brilliant.

Zach Holman’s ‘spark’ utility was absolutely an inspiration.

As I was writing up this description, I discovered I’m not the first person to write an obfuscated C sparkline utility! Vicent Martí created this one years (!) ago. (My implementation is completely independent.)