add sparkline checking

Author: hamelsmu

fastcore/xtras.py

@@ -243,13 +243,15 @@ def truncstr(s:str, maxlen:int, suf:str='…', space='')->str:
 # Cell
 def _sparkchar(x, mn, incr, empty_zero):
     if x is None or (empty_zero and not x): return ' '
+    if incr == 0: return spark_chars[0]
     res = int((x-mn)/incr-0.5)
     return spark_chars[res]
 
 # Cell
 def sparkline(data, mn=None, mx=None, empty_zero=False):
     "Sparkline for `data`, with `None`s (and zero, if `empty_zero`) shown as empty column"
     valid = [o for o in data if o is not None]
+    if not valid: return ' '
     mn,mx,n = ifnone(mn,min(valid)),ifnone(mx,max(valid)),len(spark_chars)
     res = [_sparkchar(o,mn,(mx-mn)/n,empty_zero) for o in data]
     return ''.join(res)

nbs/03_xtras.ipynb

@@ -350,7 +350,7 @@
     "    \"Reindexes collection `coll` with indices `idxs` and optional LRU cache of size `cache`\"\n",
     "    _default='coll'\n",
     "    def __init__(self, coll, idxs=None, cache=None, tfm=noop):\n",
-    "        if idxs is None: idxs = L.range(coll) \n",
+    "        if idxs is None: idxs = L.range(coll)\n",
     "        store_attr()\n",
     "        if cache is not None: self._get = functools.lru_cache(maxsize=cache)(self._get)\n",
     "\n",
@@ -1401,6 +1401,7 @@
     "#export\n",
     "def _sparkchar(x, mn, incr, empty_zero):\n",
     "    if x is None or (empty_zero and not x): return ' '\n",
+    "    if incr == 0: return spark_chars[0]\n",
     "    res = int((x-mn)/incr-0.5)\n",
     "    return spark_chars[res]"
    ]
@@ -1415,6 +1416,7 @@
     "def sparkline(data, mn=None, mx=None, empty_zero=False):\n",
     "    \"Sparkline for `data`, with `None`s (and zero, if `empty_zero`) shown as empty column\"\n",
     "    valid = [o for o in data if o is not None]\n",
+    "    if not valid: return ' '\n",
     "    mn,mx,n = ifnone(mn,min(valid)),ifnone(mx,max(valid)),len(spark_chars)\n",
     "    res = [_sparkchar(o,mn,(mx-mn)/n,empty_zero) for o in data]\n",
     "    return ''.join(res)"
@@ -1479,7 +1481,7 @@
     "            self._reset()\n",
     "        self.events +=n\n",
     "        self.last = default_timer()\n",
-    "    \n",
+    "\n",
     "    @property\n",
     "    def duration(self): return default_timer()-self.start\n",
     "    @property\n",
@@ -1587,7 +1589,7 @@
     "    def __init__(self):\n",
     "        self.missing = set()\n",
     "        super().__init__()\n",
-    "        \n",
+    "\n",
     "    def get_field(self, nm, args, kwargs):\n",
     "        try: return super().get_field(nm, args, kwargs)\n",
     "        except KeyError:\n",