A flexible utility to time the execution speed of a code snippet.

Usable from the command line or from a program.

Lib/timeit.py

@@ -0,0 +1,123 @@
+"""Framework for timing execution speed of small code snippets.
+
+This avoids a number of common traps for timing frameworks (see also
+Tim Peters' introduction to the timing chapter in the Python
+Cookbook).
+
+(To use this with older versions of Python, the dependency on the
+itertools module is easily removed; instead of itertools.repeat(None,
+count) you can use [None]*count; this is barely slower.)
+
+Command line usage:
+  python timeit.py [-n N] [-r N] [-s S] [-t] [-c] [statement]
+
+Options:
+  -n/--number N: how many times to execute 'statement' (default varies)
+  -r/--repeat N: how many times to repeat the timer (default 1)
+  -s/--setup S: statements executed once before 'statement' (default 'pass')
+  -t/--time: use time.time() (default on Unix)
+  -c/--clock: use time.clock() (default on Windows)
+  statement: statement to be timed (default 'pass')
+"""
+
+import sys
+import math
+import time
+import itertools
+
+__all__ = ["Timer"]
+
+default_number = 1000000
+default_repeat = 10
+
+if sys.platform == "win32":
+    # On Windows, the best timer is time.clock()
+    default_timer = time.clock
+else:
+    # On most other platforms the best timer is time.time()
+    default_timer = time.time
+
+template = """
+def inner(number, timer):
+    %(setup)s
+    seq = itertools.repeat(None, number)
+    t0 = timer()
+    for i in seq:
+        %(stmt)s
+    t1 = timer()
+    return t1-t0
+"""
+
+def reindent(src, indent):
+    return ("\n" + " "*indent).join(src.split("\n"))
+
+class Timer:
+
+    def __init__(self, stmt="pass", setup="pass", timer=default_timer):
+        self.timer = timer
+        stmt = reindent(stmt, 8)
+        setup = reindent(setup, 4)
+        src = template % {'stmt': stmt, 'setup': setup}
+        code = compile(src, "<src>", "exec")
+        ns = {}
+        exec code in globals(), ns
+        self.inner = ns["inner"]
+
+    def timeit(self, number=default_number):
+        return self.inner(number, self.timer)
+
+    def repeat(self, repeat=default_repeat, number=default_number):
+        r = []
+        for i in range(repeat):
+            t = self.timeit(number)
+            r.append(t)
+        return r
+
+def main(args=None):
+    if args is None:
+        args = sys.argv[1:]
+    import getopt
+    try:
+        opts, args = getopt.getopt(args, "n:s:r:tc",
+                                   ["number=", "setup=", "repeat=",
+                                    "time", "clock"])
+    except getopt.error, err:
+        print err
+        return 2
+    timer = default_timer
+    stmt = "\n".join(args) or "pass"
+    number = 0 # auto-determine
+    setup = "pass"
+    repeat = 1
+    for o, a in opts:
+        if o in ("-n", "--number"):
+            number = int(a)
+        if o in ("-s", "--setup"):
+            setup = a
+        if o in ("-r", "--repeat"):
+            repeat = int(a)
+            if repeat <= 0:
+                repeat = 1
+        if o in ("-t", "time"):
+            timer = time.time
+        if o in ("-c", "clock"):
+            timer = time.clock
+    t = Timer(stmt, setup, timer)
+    if number == 0:
+        # determine number so that 0.2 <= total time < 2.0
+        for i in range(1, 10):
+            number = 10**i
+            x = t.timeit(number)
+            if x >= 0.2:
+                break
+    r = t.repeat(repeat, number)
+    best = min(r)
+    print "%d loops," % number,
+    usec = best * 1e6 / number
+    if repeat > 1:
+        print "best of %d: %.3f usec" % (repeat, usec)
+    else:
+        print "time: %.3f usec" % usec
+
+if __name__ == "__main__":
+    sys.exit(main())