Merge pull request #792 from renato145/L_first_last

Add first and last methods to L

Author: jph00

fastcore/_modidx.py

@@ -390,10 +390,12 @@
                                      'fastcore.foundation.L.dropwhile': ('foundation.html#l.dropwhile', 'fastcore/foundation.py'),
                                      'fastcore.foundation.L.enumerate': ('foundation.html#l.enumerate', 'fastcore/foundation.py'),
                                      'fastcore.foundation.L.filter': ('foundation.html#l.filter', 'fastcore/foundation.py'),
+                                     'fastcore.foundation.L.first': ('foundation.html#l.first', 'fastcore/foundation.py'),
                                      'fastcore.foundation.L.flatmap': ('foundation.html#l.flatmap', 'fastcore/foundation.py'),
                                      'fastcore.foundation.L.flatten': ('foundation.html#l.flatten', 'fastcore/foundation.py'),
                                      'fastcore.foundation.L.groupby': ('foundation.html#l.groupby', 'fastcore/foundation.py'),
                                      'fastcore.foundation.L.itemgot': ('foundation.html#l.itemgot', 'fastcore/foundation.py'),
+                                     'fastcore.foundation.L.last': ('foundation.html#l.last', 'fastcore/foundation.py'),
                                      'fastcore.foundation.L.map': ('foundation.html#l.map', 'fastcore/foundation.py'),
                                      'fastcore.foundation.L.map_dict': ('foundation.html#l.map_dict', 'fastcore/foundation.py'),
                                      'fastcore.foundation.L.map_first': ('foundation.html#l.map_first', 'fastcore/foundation.py'),

fastcore/foundation.py

@@ -343,6 +343,20 @@ def rstarargwhere(self:L, f, negate=False):
     if negate: _f = not_(_f)
     return self._new(i for i,o in enumerate(self) if _f(o))
 
+# %% ../nbs/02_foundation.ipynb #541e7eab-3267-4156-8574-5cff8eb1a4e1
+@patch
+@curryable
+def first(self:L, f, negate=False):
+    "Return first matching item"
+    return first(self, f, negate)
+
+# %% ../nbs/02_foundation.ipynb #6fde986b-8d9b-469a-af0e-ebba11917375
+@patch
+@curryable
+def last(self:L, f, negate=False):
+    "Return last matching item"
+    return last(self, f, negate)
+
 # %% ../nbs/02_foundation.ipynb #3e7fa556
 @patch
 @curryable

nbs/02_foundation.ipynb

@@ -2510,6 +2510,102 @@
     "test_eq(L((2,1),(1,3),(3,2)).rstarargwhere(lt, negate=True), [1])"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "541e7eab-3267-4156-8574-5cff8eb1a4e1",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "#| export\n",
+    "@patch\n",
+    "@curryable\n",
+    "def first(self:L, f, negate=False):\n",
+    "    \"Return first matching item\"\n",
+    "    return first(self, f, negate)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "966ffa22-7599-4ee8-ac54-d89eedda339e",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "test_eq(t.first(lambda o:o>4), 99)\n",
+    "test_eq(t.first(lambda o:o>4,negate=True), 0)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "1664acc6-45a4-4b00-aa20-e1bcc6e2a578",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "[8, 9, None]"
+      ]
+     },
+     "execution_count": null,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "nested = L([[1,2,8,4], [5,9,7], [1,1,1]])\n",
+    "nested.map(L.first(gt(5)))"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "6fde986b-8d9b-469a-af0e-ebba11917375",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "#| export\n",
+    "@patch\n",
+    "@curryable\n",
+    "def last(self:L, f, negate=False):\n",
+    "    \"Return last matching item\"\n",
+    "    return last(self, f, negate)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "6f2a7f52-c50b-4c98-a0d5-db300b3c7fb2",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "test_eq(L(5,4,3,2,99,1).last(lambda o:o>4), 99)\n",
+    "test_eq(L(5,4,3,2,99,1).last(lambda o:o>4,negate=True), 1)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "555824ef-b4b9-45eb-8e1e-24ded3490f1f",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "[8, 7, None]"
+      ]
+     },
+     "execution_count": null,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "nested = L([[1,2,8,4], [5,9,7], [1,1,1]])\n",
+    "nested.map(L.last(gt(5)))"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,