Added contour function #688

docs/notebooks/contours.ipynb

@@ -0,0 +1,91 @@
+{
+ "cells": [
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import ee\n",
+    "import geemap\n",
+    "import geemap.colormaps as cm"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# geemap.update_package()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "Map = geemap.Map()\n",
+    "Map"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "image = ee.Image(\"USGS/SRTMGL1_003\")"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "Map.addLayer(image, {'min': 0, \"max\": 5000, \"palette\": cm.palettes.dem}, \"dem\")"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "contours = geemap.create_contours(image, 0, 5000, 200, region=None)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "Map.addLayer(contours, {'min': 0, \"max\": 5000, 'palette': cm.palettes.terrain}, 'contours')"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.8.5"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 4
+}

examples/notebooks/contours.ipynb

@@ -0,0 +1,91 @@
+{
+ "cells": [
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import ee\n",
+    "import geemap\n",
+    "import geemap.colormaps as cm"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# geemap.update_package()"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "Map = geemap.Map()\n",
+    "Map"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "image = ee.Image(\"USGS/SRTMGL1_003\")"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "Map.addLayer(image, {'min': 0, \"max\": 5000, \"palette\": cm.palettes.dem}, \"dem\")"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "contours = geemap.create_contours(image, 0, 5000, 200, region=None)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "Map.addLayer(contours, {'min': 0, \"max\": 5000, 'palette': cm.palettes.terrain}, 'contours')"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.8.5"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 4
+}

geemap/common.py

@@ -8798,3 +8798,57 @@ def temp_file_path(extension):
     file_path = os.path.join(tempfile.gettempdir(), f"{file_id}{extension}")
 
     return file_path
+
+
+def create_contours(image, min_value, max_value, interval, kernel=None, region=None):
+    """Creates contours from an image. Code adapted from https://mygeoblog.com/2017/01/28/contour-lines-in-gee. Credits to MyGeoBlog.
+
+    Args:
+        image (ee.Image): An image to create contours.
+        min_value (float): The minimum value of contours.
+        max_value (float): The maximum value of contours.
+        interval (float):  The interval between contours.
+        kernel (ee.Kernel, optional): The kernal to use for smoothing image. Defaults to None.
+        region (ee.Geometry | ee.FeatureCollection, optional): The region of interest. Defaults to None.
+
+    Raises:
+        TypeError: The image must be an ee.Image.
+        TypeError: The region must be an ee.Geometry or ee.FeatureCollection.
+
+    Returns:
+        ee.Image: The image containing contours.
+    """
+    if not isinstance(image, ee.Image):
+        raise TypeError("The image must be an ee.Image.")
+    if region is not None:
+        if isinstance(region, ee.FeatureCollection) or isinstance(region, ee.Geometry):
+            pass
+        else:
+
+            raise TypeError(
+                "The region must be an ee.Geometry or ee.FeatureCollection."
+            )
+
+    if kernel is None:
+        kernel = ee.Kernel.gaussian(5, 3)
+
+    values = ee.List.sequence(min_value, max_value, interval)
+
+    def contouring(value):
+        mycountour = (
+            image.convolve(kernel)
+            .subtract(ee.Image.constant(value))
+            .zeroCrossing()
+            .multiply(ee.Image.constant(value).toFloat())
+        )
+        return mycountour.mask(mycountour)
+
+    contours = values.map(contouring)
+
+    if region is not None:
+        if isinstance(region, ee.FeatureCollection):
+            return ee.ImageCollection(contours).mosaic().clipToCollection(region)
+        elif isinstance(region, ee.Geometry):
+            return ee.ImageCollection(contours).mosaic().clip(region)
+    else:
+        return ee.ImageCollection(contours).mosaic()

mkdocs.yml

@@ -162,6 +162,7 @@ nav:
                 - notebooks/cartoee_quickstart.ipynb
                 - notebooks/cartoee_scalebar.ipynb
                 - notebooks/cartoee_subplots.ipynb
+                - notebooks/contours.ipynb
                 - notebooks/file_browser.ipynb
                 - notebooks/geemap_and_earthengine.ipynb
                 - notebooks/geemap_and_folium.ipynb