sortperf.py

minimal python variant for small footprint apps like embedded apps

"""Sort performance test.

See main() for command line syntax.
See tabulate() for output format.

"""

import sys
import time
import whrandom
import marshal
import tempfile
import operator
import os

td = tempfile.gettempdir()

def randrange(n):
    """Return a random shuffle of range(n)."""
    fn = os.path.join(td, "rr%06d" % n)
    try:
        fp = open(fn, "rb")
    except IOError:
        result = []
        for i in range(n):
            result.append(whrandom.random())
        try:
            try:
                fp = open(fn, "wb")
                marshal.dump(result, fp)
                fp.close()
                fp = None
            finally:
                if fp:
                    try:
                        os.unlink(fn)
                    except os.error:
                        pass
        except IOError, msg:
            print "can't write", fn, ":", msg
    else:
        result = marshal.load(fp)
        fp.close()
        ##assert len(result) == n
        # Shuffle it a bit...
        for i in range(10):
            i = whrandom.randint(0, n-1)
            temp = result[:i]
            del result[:i]
            temp.reverse()
            result[len(result):] = temp
            del temp
    return result

def fl():
    sys.stdout.flush()

def doit(L):
    t0 = time.clock()
    L.sort()
    t1 = time.clock()
    print "%6.2f" % (t1-t0),
    fl()

def tabulate(r):
    """Tabulate sort speed for lists of various sizes.

    The sizes are 2**i for i in r (the argument, a list).

    The output displays i, 2**i, and the time to sort arrays of 2**i
    floating point numbers with the following properties:

    *sort: random data
    \sort: descending data
    /sort: ascending data
    ~sort: many duplicates
    -sort: all equal
    !sort: worst case scenario

    """
    cases = ("*sort", "\\sort", "/sort", "~sort", "-sort", "!sort")
    fmt = ("%2s %6s" + " %6s"*len(cases))
    print fmt % (("i", "2**i") + cases)
    for i in r:
        n = 1<<i
        L = randrange(n)
        ##assert len(L) == n
        print "%2d %6d" % (i, n),
        fl()
        doit(L) # *sort
        L.reverse()
        doit(L) # \sort
        doit(L) # /sort
        if n > 4:
            del L[4:]
            L = L*(n/4)
            L = map(lambda x: --x, L)
        doit(L) # ~sort
        del L
        L = map(abs, [-0.5]*n)
        doit(L) # -sort
        L = range(n/2-1, -1, -1)
        L[len(L):] = range(n/2)
        doit(L) # !sort
        print

def main():
    """Main program when invoked as a script.

    One argument: tabulate a single row.
    Two arguments: tabulate a range (inclusive).
    Extra arguments are used to seed the random generator.

    """
    import string
    # default range (inclusive)
    k1 = 15
    k2 = 19
    if sys.argv[1:]:
        # one argument: single point
        k1 = k2 = string.atoi(sys.argv[1])
        if sys.argv[2:]:
            # two arguments: specify range
            k2 = string.atoi(sys.argv[2])
            if sys.argv[3:]:
                # derive random seed from remaining arguments
                x, y, z = 0, 0, 0
                for a in sys.argv[3:]:
                    h = hash(a)
                    h, d = divmod(h, 256)
                    h = h & 0xffffff
                    x = (x^h^d) & 255
                    h = h>>8
                    y = (y^h^d) & 255
                    h = h>>8
                    z = (z^h^d) & 255
                whrandom.seed(x, y, z)
    r = range(k1, k2+1)                 # include the end point
    tabulate(r)

if __name__ == '__main__':
    main()