GSHHS

Prepare_gshh.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "id": "47536049",
   "metadata": {},
   "source": [
    "## Prepare latest GSHHS"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "69320ecb",
   "metadata": {},
   "outputs": [],
   "source": [
    "import geopandas as gp\n",
    "import numpy as np\n",
    "import pandas as pd\n",
    "import shapely"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "ffcdc723",
   "metadata": {},
   "outputs": [],
   "source": [
    "import matplotlib as mpl\n",
    "mpl.rcParams['agg.path.chunksize'] = 10000"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "69687495",
   "metadata": {},
   "outputs": [],
   "source": [
    "import matplotlib.pyplot as plt"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "aff3260c",
   "metadata": {},
   "outputs": [],
   "source": [
    "import cartopy.feature as cf"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "7b3d2407",
   "metadata": {},
   "outputs": [],
   "source": [
    "%matplotlib widget"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "73313b40",
   "metadata": {},
   "source": [
    "#### Old way"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "2d176eb0",
   "metadata": {},
   "source": [
    "Using the cartopy was working but then the format changed "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "9c2fe320",
   "metadata": {},
   "outputs": [],
   "source": [
    "gi = cf.GSHHSFeature(scale=\"full\", levels=[1])\n",
    "wo = gp.GeoDataFrame(geometry=[x for x in gi.geometries()])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "c42f73bc",
   "metadata": {},
   "outputs": [],
   "source": [
    "wo = wo.explode(index_parts=True).reset_index(drop=True)\n",
    "wo['area'] = wo.area\n",
    "wo = wo.sort_values(by=\"area\", ascending=0)  # sort\n",
    "wo = wo.reset_index(drop=True)\n",
    "#wo_ = wo.iloc[:100]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "928517ef",
   "metadata": {},
   "outputs": [],
   "source": [
    "wo_.plot()"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "bd391394",
   "metadata": {},
   "source": [
    "#### New way"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "2c30e64d",
   "metadata": {},
   "source": [
    "Download the latest shapefile : http://www.soest.hawaii.edu/pwessel/gshhg/gshhg-shp-2.3.7.zip"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "d71fa32e",
   "metadata": {},
   "outputs": [],
   "source": [
    "w1 = gp.read_file('/Users/brey/.local/share/cartopy/shapefiles/gshhg-shp-2/GSHHS_shp/f/GSHHS_f_L1.shp')\n",
    "w2 = gp.read_file('/Users/brey/.local/share/cartopy/shapefiles/gshhg-shp-2/GSHHS_shp/f/GSHHS_f_L6.shp')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "45785acb",
   "metadata": {},
   "outputs": [],
   "source": [
    "w5 = gp.read_file('/Users/brey/.local/share/cartopy/shapefiles/gshhg-shp-2/GSHHS_shp/f/GSHHS_f_L5.shp')"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "fc76412a",
   "metadata": {},
   "source": [
    "First check fails"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "cb564170",
   "metadata": {},
   "outputs": [],
   "source": [
    "w5.buffer(0).is_valid.all(), (w5.buffer(0).boundary.geom_type == \"LineString\").all()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "67dbfcc1",
   "metadata": {},
   "outputs": [],
   "source": [
    "# fix the first polygon\n",
    "x, y = w5.iloc[[0]].boundary[0].coords.xy\n",
    "\n",
    "x = x[2:-1]\n",
    "y = y[2:-1]\n",
    "\n",
    "\n",
    "x.append(x[-1])\n",
    "y.append(-90.)\n",
    "x.append(x[0])\n",
    "y.append(y[0])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "8ea33bde",
   "metadata": {},
   "outputs": [],
   "source": [
    "w5.loc[0:0, \"geometry\"] = shapely.Polygon(zip(x,y))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "6917a4b2",
   "metadata": {},
   "outputs": [],
   "source": [
    "x, y = w5.iloc[[1]].boundary[1].coords.xy\n",
    "x[0] = 0 \n",
    "x[1] = 0\n",
    "x[-2] = 0 \n",
    "x[-1] = 0"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "feacc558",
   "metadata": {},
   "outputs": [],
   "source": [
    "w5.loc[1:1, \"geometry\"] = shapely.Polygon(zip(x,y))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "72046e54",
   "metadata": {},
   "outputs": [],
   "source": [
    "w5_ = gp.GeoDataFrame(geometry=w5.buffer(0))"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "bb0f7528",
   "metadata": {},
   "source": [
    "After the fix, it still fails"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "3bfdcc8f",
   "metadata": {},
   "outputs": [],
   "source": [
    "w5_.buffer(0).is_valid.all(), (w5_.buffer(0).boundary.geom_type == \"LineString\").all()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "d6c2b61d",
   "metadata": {},
   "outputs": [],
   "source": [
    "w5_.iloc[[0]].boundary.explode(index_parts=True).plot(cmap='OrRd')\n",
    "s1=plt.gca()"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "910db17a",
   "metadata": {},
   "source": [
    "### merge"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "d988c5b3",
   "metadata": {},
   "outputs": [],
   "source": [
    "w1_ = gp.GeoDataFrame(geometry=w1.buffer(0))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "b0f5edd1",
   "metadata": {},
   "outputs": [],
   "source": [
    "w = gp.pd.concat([w1_,w5_])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "05599869",
   "metadata": {},
   "outputs": [],
   "source": [
    "cols = [a for a in w.columns if a not in [\"geometry\",\"area\"]]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "47da32cb",
   "metadata": {},
   "outputs": [],
   "source": [
    "w = w.drop(columns=cols)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "fe99fb36",
   "metadata": {},
   "outputs": [],
   "source": [
    "w['area'] = w.to_crs(epsg=4087).area\n",
    "w = w.explode(index_parts=True).reset_index(drop=True)\n",
    "w = w.sort_values(by=\"area\", ascending=0)  # sort\n",
    "w = w.reset_index(drop=True)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "000ad520",
   "metadata": {},
   "outputs": [],
   "source": [
    "w.boundary.plot()"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "15348cd6",
   "metadata": {},
   "source": [
    "#### Simplify"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "a6a02703",
   "metadata": {},
   "source": [
    "The `pyposeidon` utility can handle that input"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "7401b447",
   "metadata": {},
   "outputs": [],
   "source": [
    "from pyposeidon.utils.coastfix import simplify"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "3ac3831e",
   "metadata": {},
   "outputs": [],
   "source": [
    "coasts = simplify(w)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "b7d4f26f",
   "metadata": {},
   "outputs": [],
   "source": [
    "coasts.is_valid.all()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "e5d1dc03",
   "metadata": {},
   "outputs": [],
   "source": [
    "(coasts.boundary.geom_type == \"LineString\").all() # no multiLines"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "a23456d4",
   "metadata": {},
   "outputs": [],
   "source": [
    "coasts.boundary.plot()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "b18628e2",
   "metadata": {},
   "outputs": [],
   "source": [
    "#### save to file\n",
    "coasts.to_file('./coasts')"
   ]
  }
 ],
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