circle: statistics ASCII circle for analysing byte entropy in files.

circle reads all bytes in a file, and counts and arranges them from 0x00 to 0xff. Then it calculates the Standard deviation (sigma) of the data, and arranges the 256 resulting buckets in a circle, in such a way that the distance from the centre is proportional to the byte value (with 0x00 at the center, and ...0xf0-0xff bytes the farthest from it). The char that represents each byte is proportional to the deviation from the mean, in fractions of the standard deviation.

The list of different bytes counted can be printed using options -l, -L, -Z. Values over the mean will be printed green, and below it, they will be red.

Also the file can be sliced in slices of size # with -s #, or sliced in # slices with -S #.

Initial and end absolute bytes in the file can be indicated with -f # (from) and -t # (to) respectively. -T # (instead of -t) can be used to indicate the chunk size to analyze after -f # byte.

circle can be installed (as bytes-circle) in Ubuntu and Debian using official repositories. Follow these instructions for adding repositories to previous versions' linux distributions, and then just install as usual:

$ sudo apt-get install bytes-circle

There is a PPA repository available for Ubuntu (contains versions from precise to zesty):

$ sudo add-apt-repository ppa:roberto.s.galende/bytes-circle
$ sudo apt-get update
$ sudo apt-get install bytes-circle

If using R, there's a port here: https://github.com/circulosmeos/bytescircle.

There're executable files for various OS available here, including versions for Windows, HP-UX and Solaris.

Compilation:

$ gcc statistics.c circle.c -o circle -lm    

or simply

$ make   

A picture is worth a thousand words: let's circle a plain text file: the GPL v3 license:

Blue chars indicate bytes that are absent from the sample. Green represents variations above the mean, and red below it, with the size of the char directly proportional to the absolute magnitude of the deviation in fractions of sigma: from "," representing 1/4 of sigma to "@" representing 9/4 = 2.25 sigma or above. The complete list of chars is from 0 to 9:

{ '.', ',', '-', '~', ' ', '*', 'o', 'O', '#', '@' };   

A case of use can be found here: http://wp.me/p2FmmK-96.

A random file looks like:

Options for non-colored consoles (in this case chars represent increments of 0.5 sigma and zero is char '*') and for using numbers instead of ASCII art are also available: -[bnu] or -o {0|1|2|3}.

$ bytes-circle -h   

  circle v3.1 (goo.gl/TNh5dq)

Show statistics about bytes contained in a file,
as an ASCII circle graph of deviations from mean
in standard deviation (sigma) fraction increments.

Use:
  $ circle [-o {0|1|2|3}] [-bBglLZnruvh] [-[fsStT] #] [-z {0-255}] [<filename>] [<filename>] ...

  -o : show sigma as {0=default | 1=no color | 2=numbers | 3=uncoloured numbers}
  -b : no color (Black & white)
  -B : ('Break') stop processing files on first error encountered
  -g : ('Global') show summary values for file, when using `-[sS]`
  -l : list number of bytes counted, from 0 to 255
  -L : list number of bytes counted, excluding zero valued
  -Z : list number of bytes counted, but only zero valued
  -n : show sigma as Numbers
  -r : restrict statistics to the byte buckets that appear
       in the file, not to the 256 default value
  -u : show sigma as Uncoloured numbers (equivalent to `-b -n`)
  -v : print version
  -h : print this help
  -f#: ('From') analyze file from # byte on (1 implicit). SI suffixes supported.
  -s#: Slice file in slices of size # bytes. SI suffixes supported.
  -S#: Slice file in # slices. SI suffixes supported.
  -t#: ('To') analyze file until # byte. SI suffixes supported.
  -T#: ('To') analyze this # bytes from `-f`. SI suffixes supported.
  -z {0-255} : print a 2nd circle centered on this byte (0==127 !)

  Note about SI suffixes: kmgtpe (10^), KMGTPE (2^), and prefixes '0x' and '0'.

Licensed as GPL v3 or higher.