Merge pull request #33 from rubin-dp0/tickets/PREOPS-620

Simple histogram to bin categorical data

Author: leannep

02_Intermediate_TAP_Query.ipynb

@@ -428,6 +428,50 @@
     "print(f'There are {results[results[\"truth_type\"] == 3].shape[0]} SNe')"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "#### 2.4. Simple histogram to bin categorical data. \n",
+    "\n",
+    "Now we will create a simple categorical histogram of the number of each truth_type in the dataset. We will use the 'GROUP BY' ADQL command to group the Objects in the truth_match catalog by type (1: galaxies, 2:stars, 3: SNe), and the 'COUNT' command to count the number of Objects in each category. Finally we will use  the 'ORDER' command to order the results by ascending order of truth_type. "
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "query_histogram = \"SELECT truth_type, count(truth_type) \" \\\n",
+    "                  \" FROM dp01_dc2_catalogs.truth_match \" \\\n",
+    "                  \" GROUP BY truth_type \" \\\n",
+    "                  \" ORDER BY truth_type\"\n",
+    "print(query_histogram)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "object_type_histogram = service.search(query_histogram).to_table().to_pandas()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# Map the numerical values for each type to a more descriptive name\n",
+    "object_map = {1: 'galaxy', 2: 'star', 3: 'SNe'}\n",
+    "object_type_histogram['truth_type'] = \\\n",
+    "    object_type_histogram['truth_type'].map(object_map)\n",
+    "object_type_histogram"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -474,7 +518,6 @@
     "\n",
     "# We will want to filter on the truth type later\n",
     "# We will convert the truth_type integer to a more descriptive string\n",
-    "object_map = {1: 'galaxy', 2: 'star', 3: 'SNe'}\n",
     "source.data['truth_type'] = results['truth_type'].map(object_map)"
    ]
   },
@@ -784,7 +827,7 @@
     "\n",
     "# Assert that the results are the same as obtained from\n",
     "# executing synchronous queries\n",
-    "assert len(async_results) == 14424\n",
+    "assert len(async_results) == 14424 \n",
     "assert_frame_equal(results, async_results.to_table().to_pandas())"
    ]
   },