Curso python udemy

• https://www.udemy.com/course/former-python-mega-course-build-10-real-world-applications/learn/lecture/34362798#overview

• Numpy: manejo de matrices
• Web Mapping: creación mapas interactivos HTML
• Manejo Webcam
• Bokeh: libreria representación gráficos → Python Bokeh
• Pandas: libreria de analisis de datos → Python Pandas
• Flask: web development
• openCV: image processing library
• Mobile app: apk
• Web Scraping
• pyinstaller: creación de ejecutables

• sudo apt install libsqlite3-dev

• pip3 install jupyter notebook

• jupyter notebook

• Integers are used to represent whole numbers:

  rank = 10
  eggs = 12
  people = 3

• Floats represent decimal numbers:

  temperature = 10.2
  rainfall = 5.98
  elevation = 1031.88

• Strings represent text:

  message = "Welcome to our online shop!"
  name = "John"
  serial = "R001991981SW"

• Lists represent arrays of values that may change during the course of the program:

  members = ["Sim Soony", "Marry Roundknee", "Jack Corridor"]
  pixel_values = [252, 251, 251, 253, 250, 248, 247]

• Dictionaries represent pairs of keys and values:

  phone_numbers = {"John Smith": "+37682929928", "Marry Simpons": "+423998200919"}
  volcano_elevations = {"Glacier Peak": 3213.9, "Rainer": 4392.1}

• Keys of a dictionary can be extracted with:

  phone_numbers.keys()

• Values of a dictionary can be extracted with:

  phone_numbers.values()

• Tuples represent arrays of values that are not to be changed during the course of the program:

  vowels = ('a', 'e', 'i', 'o', 'u')
  one_digits = (0, 1, 2, 3, 4, 5, 6, 7, 8, 9)

• You can get a list of attributes of a data type has using:

  dir(str)
  dir(list)
  dir(dict)

• You can get a list of Python builtin functions using:

  dir(__builtins__)

• You can get the documentation of a Python data type using:

  help(str)
  help(str.replace)
  help(dict.values)

Sometimes you might need to convert between different data types in Python for one reason or another. That is very easy to do:

• From tuple to list:

  cool_tuple = (1, 2, 3)
  cool_list = list(cool_tuple)
  cool_list # [1, 2, 3]

• From list to tuple:

  cool_list = [1, 2, 3]
  cool_tuple = tuple(cool_list)
  cool_tuple # (1, 2, 3)

• From string to list:

  cool_string = "Hello"
  cool_list = list(cool_string)
  cool_list # ['H', 'e', 'l', 'l', 'o']

• From list to string:

  cool_list = ['H', 'e', 'l', 'l', 'o']
  cool_string = str.join("", cool_list)
  cool_string # 'Hello'

As can be seen above, converting a list into a string is more complex. Here str() is not sufficient. We need str.join(). Try running the code above again, but this time using str.join(«—», cool_list) in the second line. You will understand how str.join() works.

• Lists, strings, and tuples have a positive index system:

  ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]
     0      1      2      3      4      5      6

• And they have a negative index system as well:

  ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]
    -7     -6     -5     -4     -3     -2     -1

• In a list, the 2nd, 3rd, and 4th items can be accessed with:

  days = ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]
  days[1:4]
  Output: ['Tue', 'Wed', 'Thu']

• First three items of a list:

  days = ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]
  days[:3]
  Output:['Mon', 'Tue', 'Wed'] 

• Last three items of a list:

  days = ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]
  days[-3:]
  Output: ['Fri', 'Sat', 'Sun']

• Everything but the last:

  days = ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]
  days[:-1] 
  Output: ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'] 

• Everything but the last two:

  days = ["Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"]
  days[:-2] 
  Output: ['Mon', 'Tue', 'Wed', 'Thu', 'Fri'] 

• A dictionary value can be accessed using its corresponding dictionary key:

  phone_numbers = {"John":"+37682929928","Marry":"+423998200919"}
  phone_numbers["Marry"]
  Output: '+423998200919'

• Define functions:

  def cube_volume(a):
      return a * a * a

• Write if-else conditionals:

  message = "hello there"
   
  if "hello" in message:
      print("hi")
  else:
      print("I don't understand")

• Write if-elif-else conditionals:

  message = "hello there"
   
  if "hello" in message:
      print("hi")
  elif "hi" in message:
      print("hi")
  elif "hey" in message:
      print("hi")
  else:
      print("I don't understand")

• Use the and operator to check if both conditions are True at the same time:

  x = 1
  y = 1
   
  if x == 1 and y==1:
      print("Yes")
  else:
      print("No")

• Use the or operator to check if at least one condition is True:

  x = 1
  y = 2
   
  if x == 1 or y==2:
      print("Yes")
  else:
      print("No")

• Check if a value is of a particular type with isinstance:

  isinstance("abc", str)
  isinstance([1, 2, 3], list)
  # or directly:
   
  type("abc") == str
  type([1, 2, 3]) == lst

A for-loop is useful to repeatedly execute a block of code.

• You can create a for-loop like so:

  for letter in 'abc':
      print(letter.upper())

  output

  A
  B
  C

  • As you can see, the for-loop repeatedly converted all the items of 'abc' to uppercase.
  • The name after for (e.g. letter) is just a variable name
• You can loop over dictionary keys as follows:

  phone_numbers = {"John Smith":"+37682929928","Marry Simpons":"+423998200919"}
  for value in phone_numbers.keys():
      print(value)

  output

  John Smith
  Marry Simpsons

• You can loop over dictionary values:

  phone_numbers = {"John Smith":"+37682929928","Marry Simpons":"+423998200919"}
  for value in phone_numbers.values():
      print(value)

  output

  +37682929928
  +423998200919

• You can loop over dictionary items:

  phone_numbers = {"John Smith":"+37682929928","Marry Simpons":"+423998200919"}
  for key, value in phone_numbers.items():
      print(key, value)

  output

  John Smith +37682929928
  Marry Simpons +423998200919

• We also have while-loops. The code under a while-loop will run as long as the while-loop condition is true:

  while datetime.datetime.now() < datetime.datetime(2090, 8, 20, 19, 30, 20):
      print("It's not yet 19:30:20 of 2090.8.20")

  • The loop above will print out the string inside print() over and over again until the 20th of August, 2090.

A list comprehension is an expression that creates a list by iterating over another container.

• A basic list comprehension:

  [i*2 for i in [1, 5, 10]]

  output

  [2, 10, 20]

• List comprehension with if condition:

  [i*2 for i in [1, -2, 10] if i>0]

  output

  [2, 20]

• List comprehension with an if and else condition:

  [i*2 if i>0 else 0 for i in [1, -2, 10]]

  output

  [2, 0, 20]

• Functions can have more than one parameter:

  def volume(a, b, c):
      return a * b * c

• Functions can have default parameters (e.g. coefficient):

  def converter(feet, coefficient = 3.2808):
      meters = feet / coefficient
      return meters
   
  print(converter(10))
  # Output: 3.0480370641306997

• Arguments can be passed as non-keyword (positional) arguments (e.g. a) or keyword arguments (e.g. b=2 and c=10):

  def volume(a, b, c):
      return a * b * c
   
  print(volume(1, b=2, c=10))

• An *args parameter allows the function to be called with an arbitrary number of non-keyword arguments:

  def find_max(*args):
      return max(args)
  print(find_max(3, 99, 1001, 2, 8))
  # Output: 1001

• A **kwargs parameter allows the function to be called with an arbitrary number of keyword arguments:

  def find_winner(**kwargs):
      return max(kwargs, key = kwargs.get)
   
  print(find_winner(Andy = 17, Marry = 19, Sim = 45, Kae = 34))
  # Output: Sim

• Here's a summary of function elements:

• You can read an existing file with Python:

  with open("file.txt") as file:
      content = file.read()

• You can create a new file with Python and write some text on it:

  with open("file.txt", "w") as file:
      content = file.write("Sample text")

• You can append text to an existing file without overwriting it:

  with open("file.txt", "a") as file:
      content = file.write("More sample text")

• You can both append and read a file with:

  with open("file.txt", "a+") as file:
      content = file.write("Even more sample text")
      file.seek(0)
      content = file.read()

• Builtin objects are all objects that are written inside the Python interpreter in C language.
• Builtin modules contain builtins objects.
• Some builtin objects are not immediately available in the global namespace. They are parts of a builtin module. To use those objects the module needs to be imported first. E.g.:

  import time
  time.sleep(5)

• A list of all builtin modules can be printed out with:

  import sys
  sys.builtin_module_names

• Standard libraries is a jargon that includes both builtin modules written in C and also modules written in Python.
• Standard libraries written in Python reside in the Python installation directory as .py files. You can find their directory path with sys.prefix.
• Packages are a collection of .py modules.
• Third-party libraries are packages or modules written by third-party persons (not the Python core development team).
• Third-party libraries can be installed from the terminal/command line:
  • Windows:

    pip install pandas # or use 
    python -m pip install pandas # if that doesn't work.

  • Mac and Linux:

    pip3 install pandas # or use 
    python3 -m pip install pandas # if that doesn't work.

pip install Flask

script1.py

from flask import Flask, render_template
 
app=Flask(__name__)
 
@app.route("/")
def home():
    return render_template("home.html")
 
@app.route("/about")
def about():
    return render_template("about.html")
 
if __name__=="__main__":
    app.run(debug=True) 

templates/menu.html

<!DOCTYPE html>
<html>
    <head>
        <title>Flask app </title>
        <link rel="stylesheet" href="{{ url_for('static', filename='css/main.css') }}">
    </head>
    <body>
        <header>
            <div class="container">
                <h1 class="logo">Python Flask test page</h1>
                <ul class="menu">
                    <li><a href="{{ url_for('home') }}">HOME</a></li>
                    <li><a href="{{ url_for('about') }}">ABOUT</a></li>
                </u1>
            </div>
        </header>
        <div class="container">
            {%block content%}
            {%endblock%}
        </div>
    </body>
</html>

templates/home.html

{%extends "menu.html"%}
{%block content%}
    <h2>HOME PAGE</h1>
{%endblock%}

templates/about.html

{%extends "menu.html"%}
{%block content%}
    <h2>ABOUT PAGE</h1>
{%endblock%}

static/css/main.css

body {
  margin: 0;
  padding: 0;
  font-family: "Helvetica Neue", Helvetica, Arial, sans-serif;
  color: #060;
}
 
/*
 * Formatting the header area
 */
 
header {
  background-color: #DFB887;
  height: 35px;
  width: 100%;
  opacity: .9;
  margin-bottom: 10px;
}
 
header h1.logo {
  margin: 0;
  font-size: 1.7em;
  color: #fff;
  text-transform: uppercase;
  float: left;
}
 
header h1.logo:hover {
  color: #fff;
  text-decoration: none;
}
 
/*
 * Center the body content
 */
 
.container {
  width: 1200px;
  margin: 0 auto;
}
 
div.home {
  padding: 10px 0 30px 0;
  background-color: #E6E6FA;
  -webkit-border-radius: 6px;
     -moz-border-radius: 6px;
          border-radius: 6px;
}
 
div.about {
  padding: 10px 0 30px 0;
  background-color: #E6E6FA;
  -webkit-border-radius: 6px;
     -moz-border-radius: 6px;
          border-radius: 6px;
}
 
h2 {
  font-size: 3em;
  margin-top: 40px;
  text-align: center;
  letter-spacing: -2px;
}
 
h3 {
  font-size: 1.7em;
  font-weight: 100;
  margin-top: 30px;
  text-align: center;
  letter-spacing: -1px;
  color: #999;
}
 
.menu {
  float: right;
  margin-top: 8px;
}
 
.menu li {
  display: inline;
}
 
.menu li + li {
  margin-left: 35px;
}
 
.menu li a {
  color: #444;
  text-decoration: none;
}