rasterio-int8-reproject.ipynb

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    {
     "data": {
      "text/plain": [
       "'1.1.3'"
      ]
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     "execution_count": 1,
     "metadata": {},
     "output_type": "execute_result"
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   ],
   "source": [
    "import numpy as np\n",
    "import rasterio\n",
    "from affine import Affine\n",
    "import rasterio.warp\n",
    "rasterio.__version__"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([[ 0,  0,  0,  0,  0,  0,  0,  0],\n",
       "       [ 0,  0,  0,  0,  0,  0,  0,  0],\n",
       "       [ 0,  0, 88, 88, 88, 88,  0,  0],\n",
       "       [ 0,  0, 88, 88, 88, 88,  0,  0],\n",
       "       [ 0,  0, 88, 88, 88, 88,  0,  0],\n",
       "       [ 0,  0, 88, 88, 88, 88,  0,  0],\n",
       "       [ 0,  0,  0,  0,  0,  0,  0,  0],\n",
       "       [ 0,  0,  0,  0,  0,  0,  0,  0]], dtype=int8)"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "src = np.zeros((8, 8), dtype='int8')\n",
    "src[2:-2,2:-2] = 88\n",
    "src"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([[ 0,  0,  0,  0,  0,  0,  0,  0],\n",
       "       [ 0,  0,  0,  0,  0,  0,  0,  0],\n",
       "       [ 0, 88, 88, 88, 88,  0,  0,  0],\n",
       "       [ 0, 88, 88, 88, 88,  0,  0,  0],\n",
       "       [ 0, 88, 88, 88, 88,  0,  0,  0],\n",
       "       [ 0, 88, 88, 88, 88,  0,  0,  0],\n",
       "       [ 0,  0,  0,  0,  0,  0,  0,  0],\n",
       "       [ 0,  0,  0,  0,  0,  0,  0,  0]], dtype=int8)"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Shift image left by 1 pixel and Change `nodata` value to -1\n",
    "crs = 'epsg:3857'\n",
    "A = Affine.scale(10)\n",
    "\n",
    "dst = np.zeros_like(src)\n",
    "rasterio.warp.reproject(src, dst, \n",
    "                        src_crs=crs, dst_crs=crs,\n",
    "                        src_transform=A, src_nodata=0,\n",
    "                        dst_transform=A*Affine.translation(1,0), #move pixels left by 1\n",
    "                        dst_nodata=-1)\n",
    "\n",
    "# Expect edges of the array to have -1, but it's 0 instead\n",
    "# Any negative value is clamped to 0\n",
    "dst"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "array([[11, 11, 11, 11, 11, 11, 11, 11],\n",
       "       [11, 11, 11, 11, 11, 11, 11, 11],\n",
       "       [11, 88, 88, 88, 88, 11, 11, 11],\n",
       "       [11, 88, 88, 88, 88, 11, 11, 11],\n",
       "       [11, 88, 88, 88, 88, 11, 11, 11],\n",
       "       [11, 88, 88, 88, 88, 11, 11, 11],\n",
       "       [11, 11, 11, 11, 11, 11, 11, 11],\n",
       "       [11, 11, 11, 11, 11, 11, 11, 11]], dtype=int8)"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "dst = np.zeros_like(src)\n",
    "rasterio.warp.reproject(src, dst, \n",
    "                        src_crs=crs, dst_crs=crs,\n",
    "                        src_transform=A, src_nodata=0,\n",
    "                        dst_transform=A*Affine.translation(1,0), #move pixels left by 1\n",
    "                        dst_nodata=11)\n",
    "# For positive `dst_nodata` things work as expected\n",
    "dst"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "-----------------------------------------------------"
   ]
  }
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