minor fixes

rasbt · rasbt · commit d87b987f4cb2 · 2014-04-26T23:38:56.000-04:00
diff --git a/.ipynb_checkpoints/not_so_obvious_python_stuff-checkpoint.ipynb b/.ipynb_checkpoints/not_so_obvious_python_stuff-checkpoint.ipynb
@@ -1,7 +1,7 @@
 {
  "metadata": {
   "name": "",
-  "signature": "sha256:3313c0dcca1fddb3782f61571ea24bd2c1afea3d9adfb6c1c65ba959d9ce3c7e"
+  "signature": "sha256:67969145fdd440ec49d6e6976fa2ea5ffc6db16ed8c1a3f8371040f1c0e97617"
  },
  "nbformat": 3,
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@@ -59,7 +59,7 @@
      "source": [
       "# Sections\n",
       "- [The C3 class resolution algorithm for multiple class inheritance](#c3_class_res)\n",
-      "- [Using `+=` on lists creates new objects](#pm_in_lists)\n",
+      "- [Assignment operators and lists - simple-add vs. add-AND operators](#pm_in_lists)\n",
       "- [`True` and `False` in the datetime module](#datetime_module)\n",
       "- [Python reuses objects for small integers - always use \"==\" for equality, \"is\" for identity](#python_small_int)\n",
       "- [Shallow vs. deep copies if list contains other structures and objects](#shallow_vs_deep)\n",
@@ -215,7 +215,7 @@
      "cell_type": "markdown",
      "metadata": {},
      "source": [
-      "## Using `+=` on lists creates new objects"
+      "## Assignment operators and lists - simple-add vs. add-AND operators"
      ]
     },
     {
@@ -1010,7 +1010,7 @@
        ]
       }
      ],
-     "prompt_number": 29
+     "prompt_number": 7
     },
     {
      "cell_type": "markdown",
@@ -1042,7 +1042,39 @@
        ]
       }
      ],
-     "prompt_number": 30
+     "prompt_number": 9
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "And if you are really keen on using lists, there is a nifty trick that circumvents this problem as a reader nicely pointed out in the comments: We can simply pass the loop variable `i` as a default argument to the lambdas."
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "my_list = [lambda x=i: x for i in range(5)]\n",
+      "for l in my_list:\n",
+      "    print(l())"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "0\n",
+        "1\n",
+        "2\n",
+        "3\n",
+        "4\n"
+       ]
+      }
+     ],
+     "prompt_number": 10
     },
     {
      "cell_type": "markdown",
diff --git a/not_so_obvious_python_stuff.ipynb b/not_so_obvious_python_stuff.ipynb
@@ -1,7 +1,7 @@
 {
  "metadata": {
   "name": "",
-  "signature": "sha256:a53f896c4edbd7706754674c5f4b46daf5a6b5c00670d0627ddac871550f3717"
+  "signature": "sha256:67969145fdd440ec49d6e6976fa2ea5ffc6db16ed8c1a3f8371040f1c0e97617"
  },
  "nbformat": 3,
  "nbformat_minor": 0,
@@ -1010,7 +1010,7 @@
        ]
       }
      ],
-     "prompt_number": 29
+     "prompt_number": 7
     },
     {
      "cell_type": "markdown",
@@ -1042,7 +1042,39 @@
        ]
       }
      ],
-     "prompt_number": 30
+     "prompt_number": 9
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "And if you are really keen on using lists, there is a nifty trick that circumvents this problem as a reader nicely pointed out in the comments: We can simply pass the loop variable `i` as a default argument to the lambdas."
+     ]
+    },
+    {
+     "cell_type": "code",
+     "collapsed": false,
+     "input": [
+      "my_list = [lambda x=i: x for i in range(5)]\n",
+      "for l in my_list:\n",
+      "    print(l())"
+     ],
+     "language": "python",
+     "metadata": {},
+     "outputs": [
+      {
+       "output_type": "stream",
+       "stream": "stdout",
+       "text": [
+        "0\n",
+        "1\n",
+        "2\n",
+        "3\n",
+        "4\n"
+       ]
+      }
+     ],
+     "prompt_number": 10
     },
     {
      "cell_type": "markdown",
