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1 | 1 | { |
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2 | 2 | "cells": [ |
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3 | 3 | { |
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4 | 4 | "cell_type": "markdown", |
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5 | 5 | "metadata": {}, |
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6 | 6 | "source": [ |
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7 | 7 | "[Index](Index.ipynb) - [Back](Widget List.ipynb) - [Next](Widget Styling.ipynb)" |
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8 | 8 | ] |
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9 | 9 | }, |
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10 | 10 | { |
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11 | 11 | "cell_type": "markdown", |
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12 | 12 | "metadata": { |
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13 | 13 | "slideshow": { |
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14 | 14 | "slide_type": "slide" |
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15 | 15 | } |
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16 | 16 | }, |
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17 | 17 | "source": [ |
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18 | 18 | "# Widget Events" |
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19 | 19 | ] |
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20 | 20 | }, |
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21 | 21 | { |
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22 | 22 | "cell_type": "markdown", |
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23 | 23 | "metadata": {}, |
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24 | 24 | "source": [ |
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25 | 25 | "## Special events" |
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26 | 26 | ] |
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27 | 27 | }, |
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28 | 28 | { |
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29 | 29 | "cell_type": "code", |
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30 | 30 | "execution_count": null, |
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31 | 31 | "metadata": { |
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32 | 32 | "collapsed": false |
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33 | 33 | }, |
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34 | 34 | "outputs": [], |
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35 | 35 | "source": [ |
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36 | 36 | "from __future__ import print_function" |
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37 | 37 | ] |
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38 | 38 | }, |
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39 | 39 | { |
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40 | 40 | "cell_type": "markdown", |
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41 | 41 | "metadata": {}, |
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42 | 42 | "source": [ |
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43 | 43 | "The `Button` is not used to represent a data type. Instead the button widget is used to **handle mouse clicks**. The **`on_click` method** of the `Button` can be used to register function to be called when the button is clicked. The doc string of the `on_click` can be seen below." |
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44 | 44 | ] |
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45 | 45 | }, |
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46 | 46 | { |
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47 | 47 | "cell_type": "code", |
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48 | 48 | "execution_count": null, |
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49 | 49 | "metadata": { |
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50 | 50 | "collapsed": false |
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51 | 51 | }, |
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52 | 52 | "outputs": [], |
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53 | 53 | "source": [ |
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54 | 54 | "from IPython.html import widgets\n", |
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55 | 55 | "print(widgets.Button.on_click.__doc__)" |
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56 | 56 | ] |
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57 | 57 | }, |
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58 | 58 | { |
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59 | 59 | "cell_type": "markdown", |
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60 | 60 | "metadata": { |
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61 | 61 | "slideshow": { |
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62 | 62 | "slide_type": "slide" |
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63 | 63 | } |
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64 | 64 | }, |
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65 | 65 | "source": [ |
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66 | 66 | "### Example" |
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67 | 67 | ] |
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68 | 68 | }, |
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69 | 69 | { |
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70 | 70 | "cell_type": "markdown", |
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71 | 71 | "metadata": {}, |
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72 | 72 | "source": [ |
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73 | 73 | "Since button clicks are **stateless**, they are **transmitted from the front-end to the back-end using custom messages**. By using the `on_click` method, a button that prints a message when it has been clicked is shown below." |
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74 | 74 | ] |
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75 | 75 | }, |
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76 | 76 | { |
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77 | 77 | "cell_type": "code", |
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78 | 78 | "execution_count": null, |
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79 | 79 | "metadata": { |
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80 | 80 | "collapsed": false |
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81 | 81 | }, |
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82 | 82 | "outputs": [], |
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83 | 83 | "source": [ |
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84 | 84 | "from IPython.display import display\n", |
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85 | 85 | "button = widgets.Button(description=\"Click Me!\")\n", |
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86 | 86 | "display(button)\n", |
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87 | 87 | "\n", |
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88 | 88 | "def on_button_clicked(b):\n", |
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89 | 89 | " print(\"Button clicked.\")\n", |
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90 | 90 | "\n", |
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91 | 91 | "button.on_click(on_button_clicked)" |
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92 | 92 | ] |
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93 | 93 | }, |
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94 | 94 | { |
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95 | 95 | "cell_type": "markdown", |
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96 | 96 | "metadata": { |
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97 | 97 | "slideshow": { |
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98 | 98 | "slide_type": "slide" |
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99 | 99 | } |
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100 | 100 | }, |
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101 | 101 | "source": [ |
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102 | 102 | "### on_sumbit" |
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103 | 103 | ] |
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104 | 104 | }, |
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105 | 105 | { |
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106 | 106 | "cell_type": "markdown", |
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107 | 107 | "metadata": {}, |
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108 | 108 | "source": [ |
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109 | 109 | "The **`Text`** also has a special **`on_submit` event**. The `on_submit` event **fires when the user hits return**." |
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110 | 110 | ] |
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111 | 111 | }, |
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112 | 112 | { |
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113 | 113 | "cell_type": "code", |
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114 | 114 | "execution_count": null, |
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115 | 115 | "metadata": { |
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116 | 116 | "collapsed": false |
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117 | 117 | }, |
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118 | 118 | "outputs": [], |
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119 | 119 | "source": [ |
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120 | 120 | "text = widgets.Text()\n", |
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121 | 121 | "display(text)\n", |
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122 | 122 | "\n", |
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123 | 123 | "def handle_submit(sender):\n", |
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124 | 124 | " print(text.value)\n", |
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125 | 125 | "\n", |
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126 | 126 | "text.on_submit(handle_submit)" |
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127 | 127 | ] |
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128 | 128 | }, |
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129 | 129 | { |
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130 | 130 | "cell_type": "markdown", |
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131 | 131 | "metadata": { |
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132 | 132 | "slideshow": { |
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133 | 133 | "slide_type": "slide" |
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134 | 134 | } |
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135 | 135 | }, |
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136 | 136 | "source": [ |
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137 | 137 | "## Traitlet events" |
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138 | 138 | ] |
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139 | 139 | }, |
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140 | 140 | { |
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141 | 141 | "cell_type": "markdown", |
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142 | 142 | "metadata": {}, |
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143 | 143 | "source": [ |
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144 | 144 | "**Widget properties are IPython traitlets** and **traitlets are eventful**. To handle changes, the **`on_trait_change` method** of the widget can be used to **register a callback**. The doc string for `on_trait_change` can be seen below." |
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145 | 145 | ] |
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146 | 146 | }, |
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147 | 147 | { |
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148 | 148 | "cell_type": "code", |
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149 | 149 | "execution_count": null, |
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150 | 150 | "metadata": { |
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151 | 151 | "collapsed": false |
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152 | 152 | }, |
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153 | 153 | "outputs": [], |
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154 | 154 | "source": [ |
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155 | 155 | "print(widgets.Widget.on_trait_change.__doc__)" |
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156 | 156 | ] |
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157 | 157 | }, |
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158 | 158 | { |
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159 | 159 | "cell_type": "markdown", |
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160 | 160 | "metadata": { |
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161 | 161 | "slideshow": { |
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162 | 162 | "slide_type": "slide" |
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163 | 163 | } |
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164 | 164 | }, |
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165 | 165 | "source": [ |
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166 | 166 | "### Signatures" |
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167 | 167 | ] |
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168 | 168 | }, |
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169 | 169 | { |
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170 | 170 | "cell_type": "markdown", |
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171 | 171 | "metadata": {}, |
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172 | 172 | "source": [ |
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173 | 173 | "Mentioned in the doc string, the callback registered can have **4 possible signatures**:\n", |
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174 | 174 | "\n", |
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175 | 175 | "- callback()\n", |
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176 | 176 | "- callback(trait_name)\n", |
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177 | 177 | "- callback(trait_name, new_value)\n", |
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178 | 178 | "- callback(trait_name, old_value, new_value)\n", |
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179 | 179 | "\n", |
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180 | 180 | "Using this method, an example of how to output an `IntSlider`'s value as it is changed can be seen below." |
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181 | 181 | ] |
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182 | 182 | }, |
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183 | 183 | { |
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184 | 184 | "cell_type": "code", |
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185 | 185 | "execution_count": null, |
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186 | 186 | "metadata": { |
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187 | 187 | "collapsed": false |
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188 | 188 | }, |
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189 | 189 | "outputs": [], |
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190 | 190 | "source": [ |
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191 | 191 | "int_range = widgets.IntSlider()\n", |
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192 | 192 | "display(int_range)\n", |
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193 | 193 | "\n", |
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194 | 194 | "def on_value_change(name, value):\n", |
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195 | 195 | " print(value)\n", |
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196 | 196 | "\n", |
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197 | 197 | "int_range.on_trait_change(on_value_change, 'value')" |
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198 | 198 | ] |
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199 | 199 | }, |
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200 | 200 | { |
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201 | 201 | "cell_type": "markdown", |
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202 | 202 | "metadata": {}, |
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203 | 203 | "source": [ |
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204 | 204 | "# Linking Widgets" |
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205 | 205 | ] |
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206 | 206 | }, |
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207 | 207 | { |
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208 | 208 | "cell_type": "markdown", |
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209 | 209 | "metadata": {}, |
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210 | 210 | "source": [ |
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211 | 211 | "Often, you may want to simply link widget attributes together. Synchronization of attributes can be done in a simpler way than by using bare traitlets events. \n", |
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212 | 212 | "\n", |
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213 | 213 | "The first method is to use the `link` and `directional_link` functions from the `traitlets` module. " |
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214 | 214 | ] |
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215 | 215 | }, |
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216 | 216 | { |
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217 | 217 | "cell_type": "markdown", |
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218 | 218 | "metadata": {}, |
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219 | 219 | "source": [ |
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220 | 220 | "## Linking traitlets attributes from the server side" |
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221 | 221 | ] |
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222 | 222 | }, |
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223 | 223 | { |
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224 | 224 | "cell_type": "code", |
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225 | 225 | "execution_count": null, |
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226 | 226 | "metadata": { |
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227 | 227 | "collapsed": false |
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228 | 228 | }, |
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229 | 229 | "outputs": [], |
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230 | 230 | "source": [ |
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231 | 231 | "from IPython.utils import traitlets" |
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232 | 232 | ] |
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233 | 233 | }, |
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234 | 234 | { |
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235 | 235 | "cell_type": "code", |
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236 | 236 | "execution_count": null, |
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237 | 237 | "metadata": { |
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238 | 238 | "collapsed": false |
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239 | 239 | }, |
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240 | 240 | "outputs": [], |
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241 | 241 | "source": [ |
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242 | 242 | "caption = widgets.Latex(value = 'The values of slider1, slider2 and slider3 are synchronized')\n", |
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243 | 243 | "sliders1, slider2, slider3 = widgets.IntSlider(description='Slider 1'),\\\n", |
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244 | 244 | " widgets.IntSlider(description='Slider 2'),\\\n", |
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245 | 245 | " widgets.IntSlider(description='Slider 3')\n", |
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246 | 246 | "l = traitlets.link((sliders1, 'value'), (slider2, 'value'), (slider3, 'value'))\n", |
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247 | 247 | "display(caption, sliders1, slider2, slider3)" |
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248 | 248 | ] |
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249 | 249 | }, |
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250 | 250 | { |
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251 | 251 | "cell_type": "code", |
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252 | 252 | "execution_count": null, |
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253 | 253 | "metadata": { |
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254 | 254 | "collapsed": false |
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255 | 255 | }, |
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256 | 256 | "outputs": [], |
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257 | 257 | "source": [ |
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258 | 258 | "caption = widgets.Latex(value = 'Changes in source values are reflected in target1 and target2')\n", |
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259 | 259 | "source, target1, target2 = widgets.IntSlider(description='Source'),\\\n", |
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260 | 260 | " widgets.IntSlider(description='Target 1'),\\\n", |
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261 | 261 | " widgets.IntSlider(description='Target 2')\n", |
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262 | 262 | "traitlets.dlink((source, 'value'), (target1, 'value'), (target2, 'value'))\n", |
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263 | 263 | "display(caption, source, target1, target2)" |
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264 | 264 | ] |
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265 | 265 | }, |
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266 | 266 | { |
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267 | 267 | "cell_type": "markdown", |
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268 | 268 | "metadata": {}, |
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269 | 269 | "source": [ |
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270 | 270 | "Function `traitlets.link` returns a `Link` object. The link can be broken by calling the `unlink` method." |
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271 | 271 | ] |
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272 | 272 | }, |
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273 | 273 | { |
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274 | 274 | "cell_type": "code", |
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275 | 275 | "execution_count": null, |
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276 | 276 | "metadata": { |
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277 | 277 | "collapsed": false |
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278 | 278 | }, |
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279 | 279 | "outputs": [], |
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280 | 280 | "source": [ |
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281 | 281 | "# l.unlink()" |
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282 | 282 | ] |
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283 | 283 | }, |
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284 | 284 | { |
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285 | 285 | "cell_type": "markdown", |
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286 | 286 | "metadata": {}, |
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287 | 287 | "source": [ |
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288 | 288 | "## Linking widgets attributes from the client side" |
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289 | 289 | ] |
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290 | 290 | }, |
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291 | 291 | { |
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292 | 292 | "cell_type": "markdown", |
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293 | 293 | "metadata": {}, |
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294 | 294 | "source": [ |
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295 | 295 | "When synchronizing traitlets attributes, you may experience a lag because of the latency dues to the rountrip to the server side. You can also directly link widgets attributes, either in a unidirectional or a bidirectional fashion using the link widgets. " |
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296 | 296 | ] |
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297 | 297 | }, |
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298 | 298 | { |
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299 | 299 | "cell_type": "code", |
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300 | 300 | "execution_count": null, |
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301 | 301 | "metadata": { |
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302 | 302 | "collapsed": false |
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303 | 303 | }, |
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304 | 304 | "outputs": [], |
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305 | 305 | "source": [ |
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306 | 306 | "caption = widgets.Latex(value = 'The values of range1, range2 and range3 are synchronized')\n", |
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307 | 307 | "range1, range2, range3 = widgets.IntSlider(description='Range 1'),\\\n", |
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308 | 308 | " widgets.IntSlider(description='Range 2'),\\\n", |
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309 | 309 | " widgets.IntSlider(description='Range 3')\n", |
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310 | 310 | "l = widgets.jslink((range1, 'value'), (range2, 'value'), (range3, 'value'))\n", |
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311 | 311 | "display(caption, range1, range2, range3)" |
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312 | 312 | ] |
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313 | 313 | }, |
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314 | 314 | { |
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315 | 315 | "cell_type": "code", |
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316 | 316 | "execution_count": null, |
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317 | 317 | "metadata": { |
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318 | 318 | "collapsed": false |
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319 | 319 | }, |
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320 | 320 | "outputs": [], |
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321 | 321 | "source": [ |
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322 | 322 | "caption = widgets.Latex(value = 'Changes in source_range values are reflected in target_range1 and target_range2')\n", |
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323 | 323 | "source_range, target_range1, target_range2 = widgets.IntSlider(description='Source range'),\\\n", |
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324 | 324 | " widgets.IntSlider(description='Target range 1'),\\\n", |
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325 | 325 | " widgets.IntSlider(description='Target range 2')\n", |
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326 | 326 | "widgets.jsdlink((source_range, 'value'), (target_range1, 'value'), (target_range2, 'value'))\n", |
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327 | 327 | "display(caption, source_range, target_range1, target_range2)" |
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328 | 328 | ] |
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329 | 329 | }, |
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330 | 330 | { |
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331 | 331 | "cell_type": "markdown", |
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332 | 332 | "metadata": {}, |
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333 | 333 | "source": [ |
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334 | "Function `widgets.link` returns a `Link` widget. The link can be broken by calling the `unlink` method." | |
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334 | "Function `widgets.jslink` returns a `Link` widget. The link can be broken by calling the `unlink` method." | |
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335 | 335 | ] |
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336 | 336 | }, |
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337 | 337 | { |
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338 | 338 | "cell_type": "code", |
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339 | 339 | "execution_count": null, |
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340 | 340 | "metadata": { |
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341 | 341 | "collapsed": false |
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342 | 342 | }, |
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343 | 343 | "outputs": [], |
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344 | 344 | "source": [ |
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345 | 345 | "# l.unlink()" |
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346 | 346 | ] |
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347 | 347 | }, |
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348 | 348 | { |
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349 | 349 | "cell_type": "markdown", |
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350 | 350 | "metadata": {}, |
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351 | 351 | "source": [ |
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352 | 352 | "[Index](Index.ipynb) - [Back](Widget List.ipynb) - [Next](Widget Styling.ipynb)" |
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353 | 353 | ] |
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354 | 354 | } |
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355 | 355 | ], |
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356 | 356 | "metadata": { |
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357 | 357 | "cell_tags": [ |
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358 | 358 | [ |
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359 | 359 | "<None>", |
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360 | 360 | null |
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361 | 361 | ] |
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362 | 362 | ], |
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363 | 363 | "kernelspec": { |
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364 | 364 | "display_name": "Python 3", |
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365 | 365 | "language": "python", |
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366 | 366 | "name": "python3" |
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367 | 367 | }, |
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368 | 368 | "language_info": { |
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369 | 369 | "codemirror_mode": { |
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370 | 370 | "name": "ipython", |
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371 | 371 | "version": 3 |
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372 | 372 | }, |
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373 | 373 | "file_extension": ".py", |
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374 | 374 | "mimetype": "text/x-python", |
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375 | 375 | "name": "python", |
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376 | 376 | "nbconvert_exporter": "python", |
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377 | 377 | "pygments_lexer": "ipython3", |
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378 | 378 | "version": "3.4.2" |
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379 | 379 | } |
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380 | 380 | }, |
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381 | 381 | "nbformat": 4, |
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382 | 382 | "nbformat_minor": 0 |
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383 | 383 | } |
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