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Merge pull request #8 from mwcraig/update-intro
Add revised introduction notebook
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‎notebooks/01.Basics/01-OPTIONAL-More-About-Interact.ipynb

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{
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"cells": [
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"from ipywidgets import interact, interactive, fixed, interact_manual\n",
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"import ipywidgets as widgets"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"<!--NAVIGATION-->\n",
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"< [Widgets without writing widgets: interact](02.00-Using-Interact.ipynb) | [Contents](00.00-index.ipynb) | [Simple Widget Introduction](03.00-Widget_Basics.ipynb) >"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"# OPTIONAL - More about interact\n",
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"\n",
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"This notebook describes more ways to autogenerate widgets."
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## `interactive`\n",
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"\n",
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"In addition to `interact`, IPython provides another function, `interactive`, that is useful when you want to reuse the widgets that are produced or access the data that is bound to the UI controls.\n",
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"\n",
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"Note that unlike `interact`, the return value of the function will not be displayed automatically, but you can display a value inside the function with `IPython.display.display`."
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"Here is a function that displays the sum of its two arguments and returns the sum. The `display` line may be omitted if you don't want to show the result of the function."
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"from IPython.display import display\n",
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"\n",
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"def f(a, b):\n",
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" display(a + b)\n",
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" return a+b"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"Unlike `interact`, `interactive` returns a `Widget` instance rather than immediately displaying the widget."
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"w = interactive(f, a=10, b=20)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"The widget is an `interactive`, a subclass of `VBox`, which is a container for other widgets."
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"type(w)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"The children of the `interactive` are two integer-valued sliders and an output widget, produced by the widget abbreviations above."
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"w.children"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"To actually display the widgets, you can use IPython's `display` function."
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"display(w)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"At this point, the UI controls work just like they would if `interact` had been used. You can manipulate them interactively and the function will be called. However, the widget instance returned by `interactive` also gives you access to the current keyword arguments and return value of the underlying Python function. \n",
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"\n",
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"Here are the current keyword arguments. If you rerun this cell after manipulating the sliders, the values will have changed."
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"w.kwargs"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"Here is the current return value of the function."
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"w.result"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Disabling continuous updates"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"When interacting with long running functions, or even with short functions whose results take some to display, realtime feedback is a burden instead of being helpful. You might have noticed the output of some of the widgets above \"flickering\" as you adjusted the controls. By default, `interact` and `interactive` call the function for every update of the widgets value. "
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"There are two ways to mitigate this. You can either only execute on demand, or restrict execution to mouse release events."
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"### `interact_manual`"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"The `interact_manual` function provides a variant of interaction that allows you to restrict execution so it is only done on demand. A button is added to the interact controls that allows you to trigger an execute event."
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"def slow_function(i):\n",
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" \"\"\"\n",
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" Sleep for 1 second then print the argument\n",
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" \"\"\"\n",
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" from time import sleep\n",
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" print('Sleeping...')\n",
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" sleep(1)\n",
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" print(i)\n",
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"\n",
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"interact_manual(slow_function,i=widgets.FloatSlider(min=1e4, max=1e6, step=1e4));"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"You can do the same thing with `interactive` by using a `dict` as the second argument, as shown below."
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"foo = interactive(slow_function, {'manual': True}, i=widgets.FloatSlider(min=1e4, max=1e6, step=1e4))\n",
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"foo"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"### `continuous_update`"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"If you are using slider widgets, you can set the `continuous_update` kwarg to `False`. `continuous_update` is a keyword argument of slider widgets that restricts executions to mouse release events.\n",
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"\n",
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"In ipywidgets 7, the `Text` and `Textarea` controls also have a `continuous_update` argument.\n",
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"\n",
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"The first example below provides the `continuous_update` argument when the widget is created."
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"interact(slow_function,i=widgets.FloatSlider(min=1e4, max=1e6, step=5e4, continuous_update=False));"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## More control over the user interface: `interactive_output`\n",
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"\n",
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"`interactive_output` provides additional flexibility: you can control how the UI elements are laid out.\n",
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"\n",
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"Unlike `interact`, `interactive`, and `interact_manual`, `interactive_output` does not generate a user interface for the widgets. This is powerful, because it means you can create a widget, put it in a box, and then pass the widget to `interactive_output`, and have control over the widget and its layout."
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"a = widgets.IntSlider()\n",
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"b = widgets.IntSlider()\n",
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"c = widgets.IntSlider()\n",
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"\n",
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"# An HBox lays out its children horizontally\n",
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"ui = widgets.HBox([a, b, c])\n",
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"\n",
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"def f(a, b, c):\n",
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" # You can use print here instead of display because interactive_output generates a normal notebook \n",
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" # output area.\n",
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" print((a, b, c))\n",
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"\n",
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"out = widgets.interactive_output(f, {'a': a, 'b': b, 'c': c})\n",
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"\n",
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"display(ui, out)"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"# For more information \n",
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"\n",
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"For more extended examples of `interact` and `interactive`, see [the example in the ipywidgets source repository](https://github.com/jupyter-widgets/ipywidgets/blob/master/docs/source/examples/Index.ipynb)."
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"<!--NAVIGATION-->\n",
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"< [Widgets without writing widgets: interact](02.00-Using-Interact.ipynb) | [Contents](00.00-index.ipynb) | [Simple Widget Introduction](03.00-Widget_Basics.ipynb) >"
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]
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}
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],
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"metadata": {
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"kernelspec": {
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"display_name": "widgets-tutorial",
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"language": "python",
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"name": "widgets-tutorial"
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},
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"language_info": {
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"codemirror_mode": {
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"name": "ipython",
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"version": 3
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},
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"file_extension": ".py",
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"mimetype": "text/x-python",
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"name": "python",
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"nbconvert_exporter": "python",
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"pygments_lexer": "ipython3",
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"version": "3.8.3"
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}
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},
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"nbformat": 4,
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"nbformat_minor": 4
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}

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