Python3. Filling the Tank
Table of contents:
⛽️ for our rocket 🚀
Ground-up
In previous post
I tried to show you how to write simple program in neovim and
run using python3. Today I want to fill in the gaps in
your knowledge of my understanding of how developer work. First
of all we will touch on some Vim commands that migh be useful
and then we'll build a tool that show where International
Space Station is and who is currently in space. Maybe we will
call an Uber for them later, right now they have to use their scooters.
Let's start with
nvim round_globe.py
Nvim
Then please feel free to skip to the next section
if you already feel comfortable with nvim. I want to elaborate a
little bit on the subject.
So you probably want to know how to copy & paste? My solution:
<v>
" use arrow keys or h,j,k,l to highlight and...
<y>
" place cursor in the place where you want to paste and...
<P>
Do you want to reorganize your codebase and move lines around?
<V>
" highlight
<x>
" cursor in the place and...
<p>
To undo last step, use <u> and <C-r> to redo.
You can open more than one file, in separate window or tab. I show
you the tab option here.
:tabedit i_swear_i_rockyou.py
" switch to previous tab
:tabprevious
" then to close a tab and all it's windows (you know you can
" use <tab> key to autocomplete?)
:tabclose
I hope it helps.
Helpful Vim links
Once more, I encourage you to explore on theese cheatsheets and
experiment in your terminal window, tab or webshell.
If you use some flavour of Nutek, you can simply try this out
in your terminal.
w3m https://devhints.io/vim
w3m https://vim.rtorr.com/
I will teach you more about w3m later on, but to quit it - simply
<q><y>
Enough is enough
If you can't stand the pace, or my attitude, or simply want to
explore... Here's an email from freecCodeCamp where the subject is JavaScript.
Quincy Larson <quincy@freecodecamp.org>
6:11 AM (9 hours ago)
to me
Here are this week's five links that are worth your time:
1. Learn React for Beginners. This new freeCodeCamp Front-End JavaScript course will teach you all about React Hooks, State, the Context API, and more. You'll code along with three experienced software engineers, building projects step-by-step. (8 hour YouTube course): https://www.freecodecamp.org/news/learn-react-from-three-all-star-instructors/
2. And if you'd prefer to learn Angular, I'm thrilled to share this course with you as well: Learn Angular and TypeScript for Beginners. This in-depth course will teach you TypeScript Data Types, Angular Directives, Components, RxJS, and Lifecycle Hooks. (18 hour YouTube course): https://www.freecodecamp.org/news/angular-for-beginners-course/
(...)
Python class
It's not that you're my student. It's just object oriented
programming concept. Most, if not all, python types are object
and you can create your own types, classes, too. Create your
environment and I show you how to call from Houston to space.
case you forgot how to prepare your environment, here's how
python3 -m venv space_station
source space_station/bin/activate
you see now?
(space_station)% python -m pip install requests
the (space_station)% part, as it is only for reference
Import
It's time for the show to begin. Clear out your round_globe.py
file (you might need to put it in the same directory as your
environment). Starting simple, import statements. We will use
json and requests libraries. Put them in separate lines.
statemnts. What we will use.
import requests
import json
ISS
Now we go big. Whole class. ISS - International Space Station. It is
initialized without any arguments, then proceeds with a get request
to an external api resource. APIs are services on the Internet that
perform actions and/or sends data. You can even create your own and
host for other well behaved users! I check for a HTTP status code
200 - that means everything is OK and I parse the response
json data to self.lat and self.lon class instance variables. If
there is an error, we print out the status code and exit.
Then I make two methods get_lat and get_lon which return the stored
latitude and longitude ISS position variables. You can see here that
accessing instance variables, as well as functions must be prepended
with self., but you are not limited to creating only such objects.
In __init__ we can observe use of local variable response and
status_code which dies out when out of scope and you can no
longer access them from other parts of code.
The last bit of information is __str__(self) method that when used
to print object, will returned stated action replacing {} with
subsequent values.
The last thing I want to say is about indentation, namely tabs, or
spaces, which must match the hierarchical pattern and be consistent.
Otherwise you might spend much more time debugging your application
than you should.
class definition
class ISS():
# Class to represent the International Space Station
# initialize the class
def __init__(self):
# get the ISS location data
response = requests.get("http://api.open-notify.org/iss-now.json")
status_code = response.status_code
# if the response was successful, parse the JSON data
if status_code == 200:
response_json = response.json()
self.lat = response_json['iss_position']['latitude']
self.lon = response_json['iss_position']['longitude']
# if the response was not successful, print the status code and exit
else:
print("Error: " + str(status_code))
exit(1)
# return self.lat, self.lon
def get_lat(self):
return self.lat
def get_lon(self):
return self.lon
# pretty print the ISS location
def __str__(self):
return "ISS location: latitude: {}, longitude: {}" \
.format(self.get_lat(), self.get_lon())
Where we at now
To make the round_globe program much more exciting I introduce
another class that retrieves the Earth position of provided at
initialization attributes latitude and longitude. The concept
stays the same.
class definition
class PositionRelativeToEarth():
# Initialize the class
def __init__(self, latitude, longitude):
# get the position data
response = requests.get(
"https://api.bigdatacloud.net/data/reverse-geocode-client?latitude={}&longitude={}" \
.format(latitude, longitude))
status_code = response.status_code
# if the response was successful, parse the JSON data
if status_code == 200:
response_json = response.json()
self.country = response_json['countryName']
self.countryCode = response_json['countryCode']
self.city = response_json['locality']
# if the response was not successful, print the status code and exit
else:
print("Error: " + str(status_code))
exit(1)
# pretty print position
def __str__(self):
return "Position: country: {}, countryCode: {}, city: {}" \
.format(self.country, self.countryCode, self.city)
Astronauts
I want to show you, that you are not limited to sequential program
structure, and you can store methods outside of classes too. This one
gets our heroes, astronauts in space and when the method is invoked
will print out this data to console.
.get("http://api.open-notify.org/astros.json")
is in space?
def astros():
# make the request
response = requests.get("http://api.open-notify.org/astros.json")
status_code = response.status_code
# if the response was successful, parse the JSON data
if status_code == 200:
data = response.json()
# Get number of people in space.
number = data["number"]
print("Number of people in space: {}".format(number))
people = data["people"]
# Print people in space.
print("People in space: ")
for person in people:
print(person["name"])
# if the response was not successful, print the status code and exit
else:
print("Error: " + str(status_code))
exit(1)
Aggregate classes and methods
In this part of code I group all the bits provided before to contitute
a program that will run. I have to call the astros() function,
initialize ISS class and using another way of representing text data
f"{1+1}" clause I pretty print the Internationa Space Station
position relative to our globe, and at last I initilize
PositionRelativeToEarth with __init__ attributes using iss
variable.
function
def main():
astros()
iss = ISS()
print(f"{iss}")
position = PositionRelativeToEarth(iss.lat, iss.lon)
print(position)
Run the script
The last part of code tells the Python interpreter to call main
function when file is run with python or python3.
main function only if this file is executed
if __name__ == '__main__':
main()
That would be it for Today. Lookup where the International Space
Station is now and who is in the space when you please. You have me
now finished.
Cleanup
Deactivate
Deactivate command, will free you from Python's virtual environment
deactivate
Comments:
Make first impression!