01-How-to-Run-Python-Code.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<!--BOOK_INFORMATION-->\n",
    "<img align=\"left\" style=\"padding-right:10px;\" src=\"fig/cover-small.jpg\">\n",
    "\n",
    "*Este notebook es una adaptación realizada por J. Rafael Rodríguez Galván del material \"[Whirlwind Tour of Python](http://www.oreilly.com/programming/free/a-whirlwind-tour-of-python.csp)\" de Jake VanderPlas; tanto el [contenido original](https://github.com/jakevdp/WhirlwindTourOfPython) como la [adpatación actual](https://github.com/rrgalvan/PythonIntroMasterMatemat)] están disponibles en Github.*\n",
    "\n",
    "*The text and code are released under the [CC0](https://github.com/jakevdp/WhirlwindTourOfPython/blob/master/LICENSE) license; see also the companion project, the [Python Data Science Handbook](https://github.com/jakevdp/PythonDataScienceHandbook).*\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<!--NAVIGATION-->\n",
    "< [1. Introduction](00-Introduction.ipynb) | [Contents](Index.ipynb) | [A Quick Tour of Python Language Syntax](02-Basic-Python-Syntax.ipynb) >"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# How to Run Python Code"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Python is a flexible language, and there are several ways to use it depending on your particular task.\n",
    "One thing that distinguishes Python from other programming languages is that it is ***interpreted* rather than *compiled***.\n",
    "This means that it is executed line by line, which allows programming to be interactive in a way that is not directly possible with compiled languages like Fortran, C, or Java. This section will describe four primary ways you can run Python code: the *Python interpreter*, the *IPython interpreter*, via *Self-contained Scripts*, or in the *Jupyter notebook*."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 1. The Python Interpreter\n",
    "\n",
    "The most basic way to execute Python code is line by line within the *Python interpreter*.\n",
    "The Python interpreter can be started by installing the Python language (see the previous section) and typing ``python`` at the command prompt (a **shell**) (look for the Terminal on Mac OS X and Unix/Linux systems, or the Command Prompt application in Windows):\n",
    "```\n",
    "$ python\n",
    "Python 3.5.1 |Continuum Analytics, Inc.| (default, Dec  7 2015, 11:24:55)\n",
    "Type \"help\", \"copyright\", \"credits\" or \"license\" for more information.\n",
    ">>>\n",
    "```\n",
    "With the interpreter running, you can begin to type and execute code snippets.\n",
    "Here we'll use the interpreter as a simple calculator, performing calculations and assigning values to variables:\n",
    "``` python\n",
    ">>> 1 + 1\n",
    "2\n",
    ">>> x = 5\n",
    ">>> x * 3\n",
    "15\n",
    "```\n",
    "\n",
    "The interpreter makes it very convenient to try out small snippets of Python code and to experiment with short sequences of operations."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 2. The IPython interpreter\n",
    "\n",
    "If you spend much time with the basic Python interpreter, you'll find that it lacks many of the features of a full-fledged interactive development environment.\n",
    "An alternative interpreter called *IPython* (for Interactive Python) is bundled with the Anaconda distribution, and includes a host of **convenient enhancements to the basic Python interpreter**.\n",
    "It can be started by typing ``ipython`` at the command prompt:\n",
    "```\n",
    "$ ipython\n",
    "Python 3.5.1 |Continuum Analytics, Inc.| (default, Dec  7 2015, 11:24:55) \n",
    "Type \"copyright\", \"credits\" or \"license\" for more information.\n",
    "\n",
    "IPython 4.0.0 -- An enhanced Interactive Python.\n",
    "?         -> Introduction and overview of IPython's features.\n",
    "%quickref -> Quick reference.\n",
    "help      -> Python's own help system.\n",
    "object?   -> Details about 'object', use 'object??' for extra details.\n",
    "\n",
    "In [1]: \n",
    "```\n",
    "The main aesthetic difference between the Python interpreter and the enhanced IPython interpreter lies in the command prompt: Python uses ``>>>`` by default, while IPython uses numbered commands (e.g. ``In [1]:``).\n",
    "Regardless, we can execute code line by line just as we did before:\n",
    "``` ipython\n",
    "In [1]: 1 + 1\n",
    "Out[1]: 2\n",
    "\n",
    "In [2]: x = 5\n",
    "\n",
    "In [3]: x * 3\n",
    "Out[3]: 15\n",
    "```\n",
    "Note that just as the input is numbered, the output of each command is numbered as well.\n",
    "IPython makes available a wide array of useful features; for some suggestions on where to read more, see [Resources for Further Learning](16-Further-Resources.ipynb).\n",
    "\n",
    "---\n",
    "\n",
    "- **Tarea**: \n",
    "    - Abrir una shell, dentro de ella IPython y realizar algunas operaciones matemáticas sencillas. \n",
    "    - ¿Están disponibles por defecto funciones avanzadas como seno, coseno o logaritmo (`sin(x)`, `cos(x)`, `log(x)`)? \n",
    "    - Piensa que Python es un lenguaje de propósito general (como C, Java u otros) y para usar este tipo de funciones será necesario cargar una \"biblioteca\" o \"paquete\" adecuado\n",
    "    - Aprovecha para ver qué aspecto tienen los errores que se producen al intentar usar estas funciones. Como verás, los errores en Python son muy descriptivos\n",
    "\n",
    "---\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 3. Self-contained Python scripts\n",
    "\n",
    "Running Python snippets line by line is useful in some cases, but for more complicated programs it is more convenient **to save code to file, and execute it all at once**.\n",
    "By convention, Python scripts are saved in files with a *.py* extension.\n",
    "For example, let's create a script called *test.py* which contains the following:\n",
    "``` python\n",
    "# file: test.py\n",
    "print(\"Running test.py\")\n",
    "x = 5\n",
    "print(\"Result is\", 3 * x)\n",
    "```\n",
    "To run this file, we make sure it is in the current directory and type ``python`` *``filename``* at the command prompt:\n",
    "```\n",
    "$ python test.py\n",
    "Running test.py\n",
    "Result is 15\n",
    "```\n",
    "For **more complicated programs**, creating self-contained scripts like this one is a must.\n",
    "\n",
    "---\n",
    "\n",
    "- **Tarea**: \n",
    "    - Utilizar un editor de textos sencillo para escribir un script similar al anterior. \n",
    "    - Abrir una *shell* y ejecutar el *script*\n",
    "    - Localizar e instalar un editor que sea adecuado para edición de código Python. Por ejemplo, [Spyder](https://www.spyder-ide.org/) ofrece, además de un editor[especializado, una interfaz similar a la de Matlab/Octave. Existen otros editores, como [Emacs](https://www.emacswiki.org/emacs/PythonProgrammingInEmacs) (editor de gran calidad pero de uso más complejo, inicialmente), recomendables.\n",
    "\n",
    "---"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### 4. The Jupyter/IPython notebook \n",
    "\n",
    "A useful hybrid of the interactive terminal and the self-contained script is the *Jupyter notebook*, also knwon as *IPython notebook*, a document format that **allows executable code, formatted text, graphics, and even interactive features** to be **combined into a single document**.\n",
    "Though the notebook began as a Python-only format, it has since been made compatible with a large number of programming languages, and is now an essential part of the [*Jupyter Project*](https://jupyter.org/).\n",
    "The notebook is useful both as a development environment, and aFos a means of sharing work via rich computational and data-driven narratives that mix together code, figures, data, and text.\n",
    "\n",
    "---\n",
    "\n",
    "For more information and **first steps with IPython Notebook**, see e.g https://nbviewer.jupyter.org/github/nicolasfauchereau/Python_NIWA_Wellington/blob/master/notebooks/IPython_notebook.ipynb\n",
    "\n",
    "- **Tareas**:\n",
    "    - Ejecuta Ipython Notebook y crea un nuevo notebook de tipo *Python 3*\n",
    "    - Dentro de él, en una celda de código, teclea algún código Python sencillo para comprobar como funciona\n",
    "    - Crea una celda de tipo *Markdown* y escribe algún texto, incluyendo texto **negritas** y *cursivas*. Utiliza listas enumeradas y sin numeración.\n",
    "\n",
    "---\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "<!--NAVIGATION-->\n",
    "< [1. Introduction](00-Introduction.ipynb) | [Contents](Index.ipynb) | [A Quick Tour of Python Language Syntax](02-Basic-Python-Syntax.ipynb) >"
   ]
  }
 ],
 "metadata": {
  "anaconda-cloud": {},
  "kernelspec": {
   "display_name": "Python 3",
   "language": "python",
   "name": "python3"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.6.7"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 1
}