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   "source": [
    "# Computing movement speed\n",
    "\n",
    "<img align=\"right\" src=\"https://movingpandas.github.io/movingpandas/assets/img/movingpandas.png\">\n",
    "\n",
    "[![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/movingpandas/movingpandas-examples/main?filepath=1-tutorials/2-computing-speed.ipynb)\n",
    "[![IPYNB](https://img.shields.io/badge/view-ipynb-hotpink)](https://github.com/movingpandas/movingpandas-examples/blob/main/1-tutorials/2-computing-speed.ipynb)\n",
    "[![HTML](https://img.shields.io/badge/view-html-green)](https://movingpandas.github.io/movingpandas-website/1-tutorials/2-computing-speed.html)\n",
    "\n",
    "MovingPandas offers functions to compute and/or visualize the speed of movement along the trajectory between consecutive points."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "import pandas as pd\n",
    "import geopandas as gpd\n",
    "import movingpandas as mpd\n",
    "import shapely as shp\n",
    "import hvplot.pandas \n",
    "\n",
    "from geopandas import GeoDataFrame, read_file\n",
    "from shapely.geometry import Point, LineString, Polygon\n",
    "from datetime import datetime, timedelta\n",
    "from holoviews import opts\n",
    "\n",
    "import warnings\n",
    "warnings.filterwarnings('ignore')\n",
    "\n",
    "opts.defaults(opts.Overlay(active_tools=['wheel_zoom'], frame_width=500, frame_height=400))\n",
    "\n",
    "mpd.show_versions()"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Basic example"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "df = pd.DataFrame([\n",
    "  {'geometry':Point(0,0), 't':datetime(2018,1,1,12,0,0)},\n",
    "  {'geometry':Point(6,0), 't':datetime(2018,1,1,12,0,6)},\n",
    "  {'geometry':Point(6,6), 't':datetime(2018,1,1,12,0,11)},\n",
    "  {'geometry':Point(9,9), 't':datetime(2018,1,1,12,0,14)}\n",
    "]).set_index('t')\n",
    "gdf = GeoDataFrame(df, crs=31256)\n",
    "toy_traj = mpd.Trajectory(gdf, 1)\n",
    "toy_traj"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "toy_traj.add_speed(overwrite=True)\n",
    "toy_traj.df"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We can also visualize the speed values:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "toy_traj.plot(column=\"speed\", linewidth=5, capstyle='round', legend=True)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Similar to speed, we can also add other columns:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "toy_traj.add_direction(overwrite=True)\n",
    "toy_traj.df"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "toy_traj.add_timedelta(overwrite=True)\n",
    "toy_traj.df"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We can also use custom units for distance, speed, and acceleration. Allowed units include metric units from mm to km, imperial units from inch to mile, nautical miles, and non-standard units which are used as CRS distance units e.g. US Survey units."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "toy_traj.add_distance(overwrite=True, name=\"distance (km)\", units=\"km\")\n",
    "toy_traj.add_distance(overwrite=True, name=\"distance (yards)\", units=\"yd\")\n",
    "toy_traj.add_speed(overwrite=True, name=\"speed (ft/min)\", units=(\"ft\", \"min\"))\n",
    "toy_traj.add_speed(overwrite=True, name=\"speed (knots)\", units=(\"nm\", \"h\"))\n",
    "toy_traj.add_acceleration(overwrite=True, name=\"acceleration (mph/s)\", units=(\"mi\", \"h\", \"s\"))\n",
    "toy_traj.df"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Real-world trajectories"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "gdf = read_file('../data/geolife_small.gpkg')\n",
    "tc = mpd.TrajectoryCollection(gdf, 'trajectory_id', t='t')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "my_traj = tc.trajectories[1]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "my_traj.df"
   ]
  },
  {
   "attachments": {},
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Even if the ``Trajectory``/``TrajectoryCollection`` GeoDataFrame does not contain a speed column, we can still plot movement speed:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "my_traj.plot(column='speed', linewidth=5, capstyle='round', figsize=(9,3), legend=True, vmax=20)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "my_traj.hvplot(c='speed', clim=(0,20), line_width=7.0, tiles='CartoLight', cmap='Viridis', colorbar=True)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "tc.plot(column='speed', linewidth=5, capstyle='round', legend=True, vmax=20)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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