Add challenge on NumPy array slicing

novice/python/01-numpy.ipynb

@@ -1,7 +1,7 @@
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  "metadata": {
   "name": "",
-  "signature": "sha256:bdd5075bd4a75df8ed67c3124b0664471edfc1bfe6110ddcf01e68e156bcb9bb"
+  "signature": "sha256:67ffce7b022a7f2572764219cdd5dbe7d15f23c592c70db42b60d8e0aba56f40"
  },
  "nbformat": 3,
  "nbformat_minor": 0,
@@ -1247,7 +1247,38 @@
       "    i.e., a string that contains no characters.\n",
       "    If `data` holds our array of patient data,\n",
       "    what does `data[3:3, 4:4]` produce?\n",
-      "    What about `data[3:3, :]`?"
+      "    What about `data[3:3, :]`?\n",
+      "    \n",
+      "1.  For the NumPy array displayed by `print integer_data`\n",
+      "\n",
+      "    `[[ 0  2  4  6  8 10 12 14 16 18]\n",
+      "     [ 1  3  5  7  9 11 13 15 17 19]\n",
+      "     [ 2  4  6  8 10 12 14 16 18 20]\n",
+      "     [ 3  5  7  9 11 13 15 17 19 21]\n",
+      "     [ 4  6  8 10 12 14 16 18 20 22]\n",
+      "     [ 5  7  9 11 13 15 17 19 21 23]\n",
+      "     [ 6  8 10 12 14 16 18 20 22 24]\n",
+      "     [ 7  9 11 13 15 17 19 21 23 25]\n",
+      "     [ 8 10 12 14 16 18 20 22 24 26]\n",
+      "     [ 9 11 13 15 17 19 21 23 25 27]]`\n",
+      "\n",
+      "    what does `print integer_data[2:4, 3:5]` produce?\n",
+      "    \n",
+      "    1. `[[ 8 10 12]\n",
+      "        [ 9 11 13]\n",
+      "        [10 12 14]]`\n",
+      "            \n",
+      "    1. `[[ 5  7]\n",
+      "        [ 6  8]]`\n",
+      "            \n",
+      "    1. `[[ 7  9]\n",
+      "        [ 8 10]]`\n",
+      "            \n",
+      "    1. `[[ 8 10]\n",
+      "        [ 9 11]]`\n",
+      "            \n",
+      "    1. `[[12 14]\n",
+      "        [13 15]]`"
      ]
     },
     {

novice/python/01-numpy.md

@@ -562,11 +562,36 @@ last three characters: gen
     Given those answers,
     explain what `element[1:-1]` does.
 
-1.  The expression `element[3:3]` produces an [empty string](../../gloss.html#empty-string),
-    i.e., a string that contains no characters.
-    If `data` holds our array of patient data,
-    what does `data[3:3, 4:4]` produce?
-    What about `data[3:3, :]`?
+1.  For the NumPy array displayed by `print integer_data`
+
+    `[[ 0  2  4  6  8 10 12 14 16 18]
+     [ 1  3  5  7  9 11 13 15 17 19]
+     [ 2  4  6  8 10 12 14 16 18 20]
+     [ 3  5  7  9 11 13 15 17 19 21]
+     [ 4  6  8 10 12 14 16 18 20 22]
+     [ 5  7  9 11 13 15 17 19 21 23]
+     [ 6  8 10 12 14 16 18 20 22 24]
+     [ 7  9 11 13 15 17 19 21 23 25]
+     [ 8 10 12 14 16 18 20 22 24 26]
+     [ 9 11 13 15 17 19 21 23 25 27]]`
+
+    what does `print integer_data[2:4, 3:5]` produce?
+
+    1. `[[ 8 10 12]
+        [ 9 11 13]
+        [10 12 14]]`
+
+    1. `[[ 5  7]
+        [ 6  8]]`
+
+    1. `[[ 7  9]
+        [ 8 10]]`
+
+    1. `[[ 8 10]
+        [ 9 11]]`
+
+    1. `[[12 14]
+        [13 15]]`
 </div>
 
 ### Plotting