DEV Community: francnstein

itertools (python3)

francnstein — Tue, 19 May 2020 19:07:18 +0000

itertools

The module itertools is a standard library that contains several functions that are useful in functional programming.
One type of function it produces is infinite iterators.
The function count counts up infinitely from a value.
The function cycle infinitely iterates through an iterable (for instance a list or string).
The function repeat repeats an object, either infinitely or a specific number of times.

Lambda

francnstein — Fri, 15 May 2020 08:27:39 +0000

Lambda functions aren't as powerful as named functions.
They can only do things that require a single expression - usually equivalent to a single line of code.

named function

def polynomial(x):
return x**2 + 5*x + 4
print(polynomial(-4))

lambda

print((lambda x: x**2 + 5*x + 4) (-4))

0
0

String Functions (Python3)

francnstein — Fri, 08 May 2020 23:22:32 +0000

On my journey to learn my first language(python) I thought I would document anything that has helped me. As I get better and work on projects I will share them also.

Python contains many useful built-in functions and methods to accomplish common tasks.
join - joins a list of strings with another string as a separator.
replace - replaces one substring in a string with another.
startswith and endswith - determine if there is a substring at the start and end of a string, respectively.
To change the case of a string, you can use lower and upper.
The method split is the opposite of join, turning a string with a certain separator into a list.

Some things I am interested in.
https://linktr.ee/franczalezoriginals

Reverse List Slice (Python3)

francnstein — Sat, 02 May 2020 23:21:45 +0000

squares = [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
print(squares[::-1])

[81, 64, 49, 36, 25, 16, 9, 4, 1, 0]

"assertion" (python3)

francnstein — Thu, 30 Apr 2020 17:33:40 +0000

Assertions

An assertion is a sanity-check that you can turn on or turn off when you have finished testing the program.
An expression is tested, and if the result comes up false, an exception is raised.
Assertions are carried out through use of the assert statement.

print(1)
assert 2 + 2 == 4
print(2)
assert 1 + 1 == 3
print(3)

Some known Exceptions (python3)

francnstein — Wed, 29 Apr 2020 18:45:59 +0000

Exceptions

Different exceptions are raised for different reasons.
Common exceptions:
ImportError: an import fails;
IndexError: a list is indexed with an out-of-range number;
NameError: an unknown variable is used;
SyntaxError: the code can't be parsed properly;
TypeError: a function is called on a value of an inappropriate type;
ValueError: a function is called on a value of the correct type, but with an inappropriate value.

Modules (Random) PYTHON3

francnstein — Wed, 29 Apr 2020 12:10:53 +0000

Modules are pieces of code that other people have written to fulfill common tasks, such as generating random numbers, performing mathematical operations, etc.

random selects random numbers in this case 1-20

import random
for i in range(20):
value = random.randint(1,20)
print(value)

"function take an argument" (PYTHON3)

francnstein — Mon, 27 Apr 2020 00:23:03 +0000

When a function take an argument my intentions are clear :)

def say_it_loud(word):
print(word + "!")

say_it_loud("GET BETTER")
say_it_loud("KEEP CODING")
say_it_loud("HACKING HOLLYWOOD")

GET BETTER!
KEEP CODING!
HACKING HOLLYWOOD!

Blockchain dev with PYTHON3

francnstein — Sat, 25 Apr 2020 03:56:40 +0000

I started working on Blockchain dev with PYTHON. The app below gives you the balance of your Ether. A work in progress, but excited at where this will go.

"""
from web3 import Web3

infura_url = 'https://infura.io info here'
web3 = Web3(Web3.HTTPProvider(infura_url))

print(web3.isConnected())

print(web3.eth.blockNumber)

balance = web3.eth.getBalance('your key here')

print(web3.fromWei(balance, 'ether'))

"""

https://web3py.readthedocs.io/en/stable/web3.eth.html

FRANCNSTEIN © 2020 | Created 𝗐𝗂𝗍𝗁 ❤

FUNCTIONS(PYTHON3)

francnstein — Fri, 24 Apr 2020 21:24:28 +0000

You must define functions before they are called, in the same way that you must assign variables before using them.

def names():
print('Franc')
print('Francnstein')
names()

SIMPLE CALCULATOR (python3)

francnstein — Thu, 23 Apr 2020 19:02:28 +0000

I will continue to update this as I add more to it, a simple calculator using while loops if elif else statements. I love this example and can't wait to improve it.

You are now using SimpleCalc

print('What would you like to calculate?')

while True:
print('Options:')
print('Enter "add" to add two numbers')
print('Enter "subtract" to subtract two numbers')
print('Enter "multiply" to multiply two numbers')
print('Enter "divide" to divide two numbers')
print('Enter "quit" to end the program')
user_input = input(" ")

if user_input == "quit":
    break

elif user_input == "add":
    num1 = float(input('Enter a number: '))
    num2 = float(input('Enter another number: '))
    result = str(num1 + num2)
    print('The answer is ' + result)

elif user_input == "subtract":
    num1 = float(input('Enter a number: '))
    num2 = float(input('Enter another number: '))
    result = str(num1 - num2)
    print('The answer is ' + result)

elif user_input == "divide":
    num1 = float(input('Enter a number: '))
    num2 = float(input('Enter another number: '))
    result = str(num1 / num2)
    print('The answer is ' + result)

else:
    print('Unknown input')

for loops (python3)

francnstein — Wed, 22 Apr 2020 19:50:40 +0000

The for loop is commonly used to repeat some code a certain number of times. This is done by combining for loops with range objects.

------------------------------

ex.

for i in range(5):
print("hello!")

------------------------------

Now if you wanted to check if the amount of a specific letter within a string.

ex2.

name = 'HEEEELLLLLOO THHERREE'
count = 0
for letter in name:
if letter == 'E':
count = count + 1
print(count)

Note: there are easier ways to count letters within a word through built-in tools such as 'HEEEELLLLLOO THHERREE'.count(‘E’)

                                         FRANCNSTEIN © | Created 𝗐𝗂𝗍𝗁 ❤