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‎notebooks/01.06-Errors-and-Debugging.ipynb

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{
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"cells": [
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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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"<img align=\"left\" style=\"padding-right:10px;\" src=\"figures/PDSH-cover-small.png\">\n",
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"*This notebook contains an excerpt from the [Python Data Science Handbook](http://shop.oreilly.com/product/0636920034919.do) by Jake VanderPlas; the content is available [on GitHub](https://github.com/jakevdp/PythonDataScienceHandbook).*\n",
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"\n",
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"*The text is released under the [CC-BY-NC-ND license](https://creativecommons.org/licenses/by-nc-nd/3.0/us/legalcode), and code is released under the [MIT license](https://opensource.org/licenses/MIT). If you find this content useful, please support the work by [buying the book](http://shop.oreilly.com/product/0636920034919.do)!*"
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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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"# Errors and Debugging\n",
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"\n",
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"Code development and data analysis always require a bit of trial and error, and IPython contains tools to streamline this process.\n",
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"This section will briefly cover some options for controlling Python's exception reporting, followed by exploring tools for debugging errors in code."
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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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"## Controlling Exceptions: ``%xmode``\n",
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"\n",
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"Most of the time when a Python script fails, it will raise an Exception.\n",
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"When the interpreter hits one of these exceptions, information about the cause of the error can be found in the *traceback*, which can be accessed from within Python.\n",
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"With the ``%xmode`` magic function, IPython allows you to control the amount of information printed when the exception is raised.\n",
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"Consider the following code:"
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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": 1,
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"metadata": {
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"collapsed": false
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},
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"outputs": [],
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"source": [
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"def func1(a, b):\n",
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" return a / b\n",
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"\n",
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"def func2(x):\n",
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" a = x\n",
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" b = x - 1\n",
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" return func1(a, b)"
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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": 2,
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"metadata": {
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"collapsed": false
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},
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"outputs": [
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{
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"ename": "ZeroDivisionError",
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"evalue": "division by zero",
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"output_type": "error",
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"traceback": [
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"\u001b[0;31m---------------------------------------------------------------------------\u001b[0m\n\u001b[0;31mZeroDivisionError\u001b[0m Traceback (most recent call last)",
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"\u001b[0;32m<ipython-input-2-b2e110f6fc8f>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m()\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0mfunc2\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
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"\u001b[0;32m<ipython-input-1-d849e34d61fb>\u001b[0m in \u001b[0;36mfunc2\u001b[0;34m(x)\u001b[0m\n\u001b[1;32m 5\u001b[0m \u001b[0ma\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mx\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m 6\u001b[0m \u001b[0mb\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mx\u001b[0m \u001b[0;34m-\u001b[0m \u001b[0;36m1\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 7\u001b[0;31m \u001b[0;32mreturn\u001b[0m \u001b[0mfunc1\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0ma\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mb\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
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"\u001b[0;32m<ipython-input-1-d849e34d61fb>\u001b[0m in \u001b[0;36mfunc1\u001b[0;34m(a, b)\u001b[0m\n\u001b[1;32m 1\u001b[0m \u001b[0;32mdef\u001b[0m \u001b[0mfunc1\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0ma\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mb\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 2\u001b[0;31m \u001b[0;32mreturn\u001b[0m \u001b[0ma\u001b[0m \u001b[0;34m/\u001b[0m \u001b[0mb\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m\u001b[1;32m 3\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m 4\u001b[0m \u001b[0;32mdef\u001b[0m \u001b[0mfunc2\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mx\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m 5\u001b[0m \u001b[0ma\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mx\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
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"\u001b[0;31mZeroDivisionError\u001b[0m: division by zero"
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]
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}
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],
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"source": [
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"func2(1)"
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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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"Calling ``func2`` results in an error, and reading the printed trace lets us see exactly what happened.\n",
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"By default, this trace includes several lines showing the context of each step that led to the error.\n",
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"Using the ``%xmode`` magic function (short for *Exception mode*), we can change what information is printed.\n",
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"\n",
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"``%xmode`` takes a single argument, the mode, and there are three possibilities: ``Plain``, ``Context``, and ``Verbose``.\n",
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"The default is ``Context``, and gives output like that just shown before.\n",
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"``Plain`` is more compact and gives less information:"
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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": 3,
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"metadata": {
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"collapsed": false
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"Exception reporting mode: Plain\n"
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]
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}
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],
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"source": [
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"%xmode Plain"
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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": 4,
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"metadata": {
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"collapsed": false
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},
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"outputs": [
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{
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"ename": "ZeroDivisionError",
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"evalue": "division by zero",
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"output_type": "error",
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"traceback": [
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"Traceback \u001b[0;36m(most recent call last)\u001b[0m:\n",
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" File \u001b[1;32m\"<ipython-input-4-b2e110f6fc8f>\"\u001b[0m, line \u001b[1;32m1\u001b[0m, in \u001b[1;35m<module>\u001b[0m\n func2(1)\n",
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" File \u001b[1;32m\"<ipython-input-1-d849e34d61fb>\"\u001b[0m, line \u001b[1;32m7\u001b[0m, in \u001b[1;35mfunc2\u001b[0m\n return func1(a, b)\n",
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"\u001b[0;36m File \u001b[0;32m\"<ipython-input-1-d849e34d61fb>\"\u001b[0;36m, line \u001b[0;32m2\u001b[0;36m, in \u001b[0;35mfunc1\u001b[0;36m\u001b[0m\n\u001b[0;31m return a / b\u001b[0m\n",
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"\u001b[0;31mZeroDivisionError\u001b[0m\u001b[0;31m:\u001b[0m division by zero\n"
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]
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}
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],
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"source": [
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"func2(1)"
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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 ``Verbose`` mode adds some extra information, including the arguments to any functions that are called:"
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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": 5,
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"metadata": {
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"collapsed": false
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"Exception reporting mode: Verbose\n"
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]
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}
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],
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"source": [
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"%xmode Verbose"
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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": 6,
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"metadata": {
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"collapsed": false
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},
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"outputs": [
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{
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"ename": "ZeroDivisionError",
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"evalue": "division by zero",
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"output_type": "error",
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"traceback": [
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"\u001b[0;31m---------------------------------------------------------------------------\u001b[0m\n\u001b[0;31mZeroDivisionError\u001b[0m Traceback (most recent call last)",
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"\u001b[0;32m<ipython-input-6-b2e110f6fc8f>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m()\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0mfunc2\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m \u001b[0;36mglobal\u001b[0m \u001b[0;36mfunc2\u001b[0m \u001b[0;34m= <function func2 at 0x103729320>\u001b[0m\n",
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"\u001b[0;32m<ipython-input-1-d849e34d61fb>\u001b[0m in \u001b[0;36mfunc2\u001b[0;34m(x=1)\u001b[0m\n\u001b[1;32m 5\u001b[0m \u001b[0ma\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mx\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m 6\u001b[0m \u001b[0mb\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mx\u001b[0m \u001b[0;34m-\u001b[0m \u001b[0;36m1\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 7\u001b[0;31m \u001b[0;32mreturn\u001b[0m \u001b[0mfunc1\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0ma\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mb\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m \u001b[0;36mglobal\u001b[0m \u001b[0;36mfunc1\u001b[0m \u001b[0;34m= <function func1 at 0x1037294d0>\u001b[0m\u001b[0;34m\n \u001b[0m\u001b[0;36ma\u001b[0m \u001b[0;34m= 1\u001b[0m\u001b[0;34m\n \u001b[0m\u001b[0;36mb\u001b[0m \u001b[0;34m= 0\u001b[0m\n",
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"\u001b[0;32m<ipython-input-1-d849e34d61fb>\u001b[0m in \u001b[0;36mfunc1\u001b[0;34m(a=1, b=0)\u001b[0m\n\u001b[1;32m 1\u001b[0m \u001b[0;32mdef\u001b[0m \u001b[0mfunc1\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0ma\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mb\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m----> 2\u001b[0;31m \u001b[0;32mreturn\u001b[0m \u001b[0ma\u001b[0m \u001b[0;34m/\u001b[0m \u001b[0mb\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m \u001b[0;36ma\u001b[0m \u001b[0;34m= 1\u001b[0m\u001b[0;34m\n \u001b[0m\u001b[0;36mb\u001b[0m \u001b[0;34m= 0\u001b[0m\n\u001b[1;32m 3\u001b[0m \u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m 4\u001b[0m \u001b[0;32mdef\u001b[0m \u001b[0mfunc2\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mx\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m 5\u001b[0m \u001b[0ma\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mx\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
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"\u001b[0;31mZeroDivisionError\u001b[0m: division by zero"
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]
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}
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],
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"source": [
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"func2(1)"
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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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"This extra information can help narrow-in on why the exception is being raised.\n",
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"So why not use the ``Verbose`` mode all the time?\n",
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"As code gets complicated, this kind of traceback can get extremely long.\n",
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"Depending on the context, sometimes the brevity of ``Default`` mode is easier to work with."
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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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"## Debugging: When Reading Tracebacks Is Not Enough\n",
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"\n",
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"The standard Python tool for interactive debugging is ``pdb``, the Python debugger.\n",
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"This debugger lets the user step through the code line by line in order to see what might be causing a more difficult error.\n",
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"The IPython-enhanced version of this is ``ipdb``, the IPython debugger.\n",
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"\n",
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"There are many ways to launch and use both these debuggers; we won't cover them fully here.\n",
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"Refer to the online documentation of these two utilities to learn more.\n",
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"\n",
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"In IPython, perhaps the most convenient interface to debugging is the ``%debug`` magic command.\n",
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"If you call it after hitting an exception, it will automatically open an interactive debugging prompt at the point of the exception.\n",
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"The ``ipdb`` prompt lets you explore the current state of the stack, explore the available variables, and even run Python commands!\n",
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"\n",
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"Let's look at the most recent exception, then do some basic tasks–print the values of ``a`` and ``b``, and type ``quit`` to quit the debugging session:"
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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": 7,
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"metadata": {
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"collapsed": false
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"> \u001b[0;32m<ipython-input-1-d849e34d61fb>\u001b[0m(2)\u001b[0;36mfunc1\u001b[0;34m()\u001b[0m\n",
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"\u001b[0;32m 1 \u001b[0;31m\u001b[0;32mdef\u001b[0m \u001b[0mfunc1\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0ma\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mb\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
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"\u001b[0m\u001b[0;32m----> 2 \u001b[0;31m \u001b[0;32mreturn\u001b[0m \u001b[0ma\u001b[0m \u001b[0;34m/\u001b[0m \u001b[0mb\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
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"\u001b[0m\u001b[0;32m 3 \u001b[0;31m\u001b[0;34m\u001b[0m\u001b[0m\n",
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"\u001b[0m\n",
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"ipdb> print(a)\n",
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"1\n",
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"ipdb> print(b)\n",
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"0\n",
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"ipdb> quit\n"
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]
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}
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],
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"source": [
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"%debug"
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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 interactive debugger allows much more than this, though–we can even step up and down through the stack and explore the values of variables there:"
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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": 8,
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"metadata": {
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"collapsed": false
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},
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"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"> \u001b[0;32m<ipython-input-1-d849e34d61fb>\u001b[0m(2)\u001b[0;36mfunc1\u001b[0;34m()\u001b[0m\n",
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"\u001b[0;32m 1 \u001b[0;31m\u001b[0;32mdef\u001b[0m \u001b[0mfunc1\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0ma\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mb\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
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"\u001b[0m\u001b[0;32m----> 2 \u001b[0;31m \u001b[0;32mreturn\u001b[0m \u001b[0ma\u001b[0m \u001b[0;34m/\u001b[0m \u001b[0mb\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
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"\u001b[0m\u001b[0;32m 3 \u001b[0;31m\u001b[0;34m\u001b[0m\u001b[0m\n",
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"\u001b[0m\n",
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"ipdb> up\n",
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"> \u001b[0;32m<ipython-input-1-d849e34d61fb>\u001b[0m(7)\u001b[0;36mfunc2\u001b[0;34m()\u001b[0m\n",
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"\u001b[0;32m 5 \u001b[0;31m \u001b[0ma\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mx\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
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"\u001b[0m\u001b[0;32m 6 \u001b[0;31m \u001b[0mb\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mx\u001b[0m \u001b[0;34m-\u001b[0m \u001b[0;36m1\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
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"\u001b[0m\u001b[0;32m----> 7 \u001b[0;31m \u001b[0;32mreturn\u001b[0m \u001b[0mfunc1\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0ma\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mb\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
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"\u001b[0m\n",
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"ipdb> print(x)\n",
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"1\n",
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"ipdb> up\n",
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"> \u001b[0;32m<ipython-input-6-b2e110f6fc8f>\u001b[0m(1)\u001b[0;36m<module>\u001b[0;34m()\u001b[0m\n",
273+
"\u001b[0;32m----> 1 \u001b[0;31m\u001b[0mfunc2\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
274+
"\u001b[0m\n",
275+
"ipdb> down\n",
276+
"> \u001b[0;32m<ipython-input-1-d849e34d61fb>\u001b[0m(7)\u001b[0;36mfunc2\u001b[0;34m()\u001b[0m\n",
277+
"\u001b[0;32m 5 \u001b[0;31m \u001b[0ma\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mx\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
278+
"\u001b[0m\u001b[0;32m 6 \u001b[0;31m \u001b[0mb\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mx\u001b[0m \u001b[0;34m-\u001b[0m \u001b[0;36m1\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
279+
"\u001b[0m\u001b[0;32m----> 7 \u001b[0;31m \u001b[0;32mreturn\u001b[0m \u001b[0mfunc1\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0ma\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mb\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
280+
"\u001b[0m\n",
281+
"ipdb> quit\n"
282+
]
283+
}
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],
285+
"source": [
286+
"%debug"
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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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"This allows you to quickly find out not only what caused the error, but what function calls led up to the error.\n",
294+
"\n",
295+
"If you'd like the debugger to launch automatically whenever an exception is raised, you can use the ``%pdb`` magic function to turn on this automatic behavior:"
296+
]
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},
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{
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"cell_type": "code",
300+
"execution_count": 9,
301+
"metadata": {
302+
"collapsed": false
303+
},
304+
"outputs": [
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
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"Exception reporting mode: Plain\n",
310+
"Automatic pdb calling has been turned ON\n"
311+
]
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},
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{
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"ename": "ZeroDivisionError",
315+
"evalue": "division by zero",
316+
"output_type": "error",
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"traceback": [
318+
"Traceback \u001b[0;36m(most recent call last)\u001b[0m:\n",
319+
" File \u001b[1;32m\"<ipython-input-9-569a67d2d312>\"\u001b[0m, line \u001b[1;32m3\u001b[0m, in \u001b[1;35m<module>\u001b[0m\n func2(1)\n",
320+
" File \u001b[1;32m\"<ipython-input-1-d849e34d61fb>\"\u001b[0m, line \u001b[1;32m7\u001b[0m, in \u001b[1;35mfunc2\u001b[0m\n return func1(a, b)\n",
321+
"\u001b[0;36m File \u001b[0;32m\"<ipython-input-1-d849e34d61fb>\"\u001b[0;36m, line \u001b[0;32m2\u001b[0;36m, in \u001b[0;35mfunc1\u001b[0;36m\u001b[0m\n\u001b[0;31m return a / b\u001b[0m\n",
322+
"\u001b[0;31mZeroDivisionError\u001b[0m\u001b[0;31m:\u001b[0m division by zero\n"
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]
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},
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{
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"name": "stdout",
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"output_type": "stream",
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"text": [
329+
"> \u001b[0;32m<ipython-input-1-d849e34d61fb>\u001b[0m(2)\u001b[0;36mfunc1\u001b[0;34m()\u001b[0m\n",
330+
"\u001b[0;32m 1 \u001b[0;31m\u001b[0;32mdef\u001b[0m \u001b[0mfunc1\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0ma\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mb\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
331+
"\u001b[0m\u001b[0;32m----> 2 \u001b[0;31m \u001b[0;32mreturn\u001b[0m \u001b[0ma\u001b[0m \u001b[0;34m/\u001b[0m \u001b[0mb\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n",
332+
"\u001b[0m\u001b[0;32m 3 \u001b[0;31m\u001b[0;34m\u001b[0m\u001b[0m\n",
333+
"\u001b[0m\n",
334+
"ipdb> print(b)\n",
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"0\n",
336+
"ipdb> quit\n"
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]
338+
}
339+
],
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"source": [
341+
"%xmode Plain\n",
342+
"%pdb on\n",
343+
"func2(1)"
344+
]
345+
},
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{
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"cell_type": "markdown",
348+
"metadata": {},
349+
"source": [
350+
"Finally, if you have a script that you'd like to run from the beginning in interactive mode, you can run it with the command ``%run -d``, and use the ``next`` command to step through the lines of code interactively."
351+
]
352+
},
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{
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"cell_type": "markdown",
355+
"metadata": {},
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"source": [
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"### Partial list of debugging commands\n",
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"\n",
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"There are many more available commands for interactive debugging than we've listed here; the following table contains a description of some of the more common and useful ones:\n",
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"\n",
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"| Command | Description |\n",
362+
"|-----------------|-------------------------------------------------------------|\n",
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"| ``list`` | Show the current ___location in the file |\n",
364+
"| ``h(elp)`` | Show a list of commands, or find help on a specific command |\n",
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"| ``q(uit)`` | Quit the debugger and the program |\n",
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"| ``c(ontinute)`` | Quit the debugger, continue in the program |\n",
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"| ``n(ext)`` | Go to the next step of the program |\n",
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"| ``<enter>`` | Repeat the previous command |\n",
369+
"| ``p(rint)`` | Print variables |\n",
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"| ``s(tep)`` | Step into a subroutine |\n",
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"| ``r(eturn)`` | Return out of a subroutine |\n",
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"\n",
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"For more information, use the ``help`` command in the debugger, or take a look at ``ipdb``'s [online documentation](https://github.com/gotcha/ipdb)."
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]
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}
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],
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"metadata": {
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"anaconda-cloud": {},
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"kernelspec": {
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"display_name": "Python [default]",
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"language": "python",
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"name": "python3"
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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": "3.5.1"
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}
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},
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"nbformat": 4,
398+
"nbformat_minor": 0
399+
}

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