{
  "cells": [
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "\n# Ways to set a color's alpha value\n\nCompare setting alpha by the *alpha* keyword argument and by one of the Matplotlib color\nformats. Often, the *alpha* keyword is the only tool needed to add transparency to a\ncolor. In some cases, the *(matplotlib_color, alpha)* color format provides an easy way\nto fine-tune the appearance of a Figure.\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "import matplotlib.pyplot as plt\nimport numpy as np\n\n# Fixing random state for reproducibility.\nnp.random.seed(19680801)\n\nfig, (ax1, ax2) = plt.subplots(ncols=2, figsize=(8, 4))\n\nx_values = [n for n in range(20)]\ny_values = np.random.randn(20)\n\nfacecolors = ['green' if y > 0 else 'red' for y in y_values]\nedgecolors = facecolors\n\nax1.bar(x_values, y_values, color=facecolors, edgecolor=edgecolors, alpha=0.5)\nax1.set_title(\"Explicit 'alpha' keyword value\\nshared by all bars and edges\")\n\n\n# Normalize y values to get distinct face alpha values.\nabs_y = [abs(y) for y in y_values]\nface_alphas = [n / max(abs_y) for n in abs_y]\nedge_alphas = [1 - alpha for alpha in face_alphas]\n\ncolors_with_alphas = list(zip(facecolors, face_alphas))\nedgecolors_with_alphas = list(zip(edgecolors, edge_alphas))\n\nax2.bar(x_values, y_values, color=colors_with_alphas,\n        edgecolor=edgecolors_with_alphas)\nax2.set_title('Normalized alphas for\\neach bar and each edge')\n\nplt.show()"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        ".. admonition:: References\n\n   The use of the following functions, methods, classes and modules is shown\n   in this example:\n\n   - `matplotlib.axes.Axes.bar`\n   - `matplotlib.pyplot.subplots`\n\n.. tags::\n\n   styling: color\n   plot-type: bar\n   level: beginner\n\n"
      ]
    }
  ],
  "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": "3.13.2"
    }
  },
  "nbformat": 4,
  "nbformat_minor": 0
}