indexing

Author: keewis

intermediate/hierarchical_computation.ipynb

@@ -84,6 +84,36 @@
    "cell_type": "markdown",
    "id": "6",
    "metadata": {},
+   "source": [
+    "## Indexing\n",
+    "\n",
+    "Just like arithmetic, indexing is simply forwarded to the node datasets. The only difference is that nodes that don't have a certain coordinate / dimension are skipped instead of raising an error:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "7",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "tree.isel(lat=slice(None, 10))"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "8",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "tree.sel(time=\"2013-11\")"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "9",
+   "metadata": {},
    "source": [
     "## Reductions\n",
     "\n",
@@ -93,7 +123,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "7",
+   "id": "10",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -102,7 +132,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "8",
+   "id": "11",
    "metadata": {},
    "source": [
     "## Applying functions designed for `Dataset` with `map_over_datasets`\n",
@@ -113,7 +143,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "9",
+   "id": "12",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -122,7 +152,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "10",
+   "id": "13",
    "metadata": {},
    "source": [
     "Note how the result is a empty `Dataset`?\n",
@@ -133,7 +163,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "11",
+   "id": "14",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -142,7 +172,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "12",
+   "id": "15",
    "metadata": {},
    "source": [
     "We can also use a custom function to perform more complex operations, like subtracting a group mean:"
@@ -151,7 +181,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "13",
+   "id": "16",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -161,7 +191,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "14",
+   "id": "17",
    "metadata": {},
    "source": [
     "Applying that to the dataset raises an error, though:"
@@ -170,7 +200,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "15",
+   "id": "18",
    "metadata": {},
    "outputs": [],
    "source": [
@@ -179,7 +209,7 @@
   },
   {
    "cell_type": "markdown",
-   "id": "16",
+   "id": "19",
    "metadata": {},
    "source": [
     "The reason for this error is that the root node does not have any variables, and thus in particular no `\"time\"` coordinate. To avoid the error, we have to skip computing the function for that node:"
@@ -188,7 +218,7 @@
   {
    "cell_type": "code",
    "execution_count": null,
-   "id": "17",
+   "id": "20",
    "metadata": {},
    "outputs": [],
    "source": [