fixes #248

Author: jph00

fastcore/_nbdev.py

@@ -158,6 +158,7 @@
          "Path.mk_write": "03_xtras.ipynb",
          "Path.ls": "03_xtras.ipynb",
          "Path.__repr__": "03_xtras.ipynb",
+         "time_events": "03_xtras.ipynb",
          "stringfmt_names": "03_xtras.ipynb",
          "PartialFormatter": "03_xtras.ipynb",
          "partial_format": "03_xtras.ipynb",

fastcore/xtras.py

@@ -2,9 +2,9 @@
 
 __all__ = ['dict2obj', 'obj2dict', 'repr_dict', 'is_listy', 'shufflish', 'mapped', 'IterLen', 'ReindexCollection',
            'maybe_open', 'image_size', 'bunzip', 'join_path_file', 'loads', 'untar_dir', 'repo_details', 'run',
-           'open_file', 'save_pickle', 'load_pickle', 'stringfmt_names', 'PartialFormatter', 'partial_format',
-           'utc2local', 'local2utc', 'trace', 'round_multiple', 'modified_env', 'ContextManagers', 'str2bool',
-           'sort_by_run']
+           'open_file', 'save_pickle', 'load_pickle', 'time_events', 'stringfmt_names', 'PartialFormatter',
+           'partial_format', 'utc2local', 'local2utc', 'trace', 'round_multiple', 'modified_env', 'ContextManagers',
+           'str2bool', 'sort_by_run']
 
 # Cell
 from .imports import *
@@ -17,6 +17,7 @@
 from contextlib import contextmanager,ExitStack
 from pdb import set_trace
 from datetime import datetime, timezone
+from timeit import default_timer
 
 # Cell
 def dict2obj(d):
@@ -220,6 +221,12 @@ def __repr__(self:Path):
         except: pass
     return f"Path({self.as_posix()!r})"
 
+# Cell
+def time_events():
+    "A simple event timer implemented as a coroutine"
+    start,events = default_timer(),0
+    while True: events += (yield events,events/(default_timer()-start)) or 0
+
 # Cell
 _fmt = string.Formatter()
 

nbs/03_xtras.ipynb

@@ -25,7 +25,8 @@
     "import imghdr,struct,distutils.util,tempfile,time,string\n",
     "from contextlib import contextmanager,ExitStack\n",
     "from pdb import set_trace\n",
-    "from datetime import datetime, timezone"
+    "from datetime import datetime, timezone\n",
+    "from timeit import default_timer"
    ]
   },
   {
@@ -36,7 +37,8 @@
    "source": [
     "from fastcore.test import *\n",
     "from nbdev.showdoc import *\n",
-    "from fastcore.nb_imports import *"
+    "from fastcore.nb_imports import *\n",
+    "from time import sleep"
    ]
   },
   {
@@ -376,7 +378,7 @@
       "text/markdown": [
        "<h4 id=\"ReindexCollection\" class=\"doc_header\"><code>class</code> <code>ReindexCollection</code><a href=\"\" class=\"source_link\" style=\"float:right\">[source]</a></h4>\n",
        "\n",
-       "> <code>ReindexCollection</code>(**`coll`**, **`idxs`**=*`None`*, **`cache`**=*`None`*, **`tfm`**=*`noop`*) :: [`GetAttr`](/foundation.html#GetAttr)\n",
+       "> <code>ReindexCollection</code>(**`coll`**, **`idxs`**=*`None`*, **`cache`**=*`None`*, **`tfm`**=*`noop`*) :: [`GetAttr`](/basics.html#GetAttr)\n",
        "\n",
        "Reindexes collection `coll` with indices `idxs` and optional LRU cache of size `cache`"
       ],
@@ -616,7 +618,7 @@
     {
      "data": {
       "text/plain": [
-       "['f', 'd', 'e', 'g', 'a', 'b', 'h', 'c']"
+       "['d', 'h', 'g', 'a', 'c', 'f', 'e', 'b']"
       ]
      },
      "execution_count": null,
@@ -1317,6 +1319,50 @@
     "## Other Helpers"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "#export\n",
+    "def time_events():\n",
+    "    \"A simple event timer implemented as a coroutine\"\n",
+    "    start,events = default_timer(),0\n",
+    "    while True: events += (yield events,events/(default_timer()-start)) or 0"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "This is convenient for tracking the frequency of events. Call `send(None)` to start the timer, and then call `send(n)` any time you want to add `n` events to the counter. Pass the object to `next()` to get a tuple of the number of events and the frequency/second."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "# Events: 10, Freq/sec: 64.50\n"
+     ]
+    }
+   ],
+   "source": [
+    "# Random wait function for testing `time_events`\n",
+    "def _randwait(): yield from (sleep(random.random()/30) for _ in range(10))\n",
+    "\n",
+    "c = time_events()\n",
+    "c.send(None)                     # Start timer by sending `None`\n",
+    "for o in _randwait(): c.send(1)  # Send an event\n",
+    "events,freq = next(c)            # `next` returns counter values\n",
+    "print(f'# Events: {events}, Freq/sec: {freq:.02f}')"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,