{
  "cells": [
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "\n# Demo connected components\n\nExtracting and labeling connected components in a 2D array\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "import numpy as np\nimport matplotlib.pyplot as plt"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Generate some binary data\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "x, y = np.indices((100, 100))\nsig = (\n    np.sin(2 * np.pi * x / 50.0)\n    * np.sin(2 * np.pi * y / 50.0)\n    * (1 + x * y / 50.0**2) ** 2\n)\nmask = sig > 1\n\nplt.figure(figsize=(7, 3.5))\nplt.subplot(1, 2, 1)\nplt.imshow(sig)\nplt.axis(\"off\")\nplt.title(\"sig\")\n\nplt.subplot(1, 2, 2)\nplt.imshow(mask, cmap=\"gray\")\nplt.axis(\"off\")\nplt.title(\"mask\")\nplt.subplots_adjust(wspace=0.05, left=0.01, bottom=0.01, right=0.99, top=0.9)"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Label connected components\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "import scipy as sp\n\nlabels, nb = sp.ndimage.label(mask)\n\nplt.figure(figsize=(3.5, 3.5))\nplt.imshow(labels)\nplt.title(\"label\")\nplt.axis(\"off\")\n\nplt.subplots_adjust(wspace=0.05, left=0.01, bottom=0.01, right=0.99, top=0.9)"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "Extract the 4th connected component, and crop the array around it\n\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "sl = sp.ndimage.find_objects(labels == 4)\nplt.figure(figsize=(3.5, 3.5))\nplt.imshow(sig[sl[0]])\nplt.title(\"Cropped connected component\")\nplt.axis(\"off\")\n\nplt.subplots_adjust(wspace=0.05, left=0.01, bottom=0.01, right=0.99, top=0.9)\n\nplt.show()"
      ]
    }
  ],
  "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": "3.12.11"
    }
  },
  "nbformat": 4,
  "nbformat_minor": 0
}