Plutonic Rainbows

Apple Credit Card

Apple getting into credit cards. I feel deeply uneasy about this but I don’t know exactly why. I think it’s an uncomfortable look for them but hey, it’s yet another potential revenue stream and money is what matters - don’t let Apple ever convince you of anything else - despite all the empty platitudes and virtue-signalling at their events. Also don’t be fooled by the Apple privacy hype. Goldman Sachs are apparently being trusted with all the information.

The Verge:

Similarly, Apple’s approach to data privacy differs from other credit card companies: Apple is banking on Goldman Sachs to secure users’ credit card data, which also means that Apple won’t be the one held responsible in the event of a breach. Again, Goldman Sachs declined to comment.

I don’t think this is going to be anywhere near as exclusive as all the Apple fans would like - despite the Titanium design. American Express and Chase Sapphire (among others) are where the (relative) exclusivity lies with ownership fees as much as $550 just to own the card for one year. This is more like a tier 2 card rather than a 4 or 5 offering.

In addition, metal cards are very much a USA/Canada thing; Europe not so much. Amex in the UK don’t offer any cards in metal despite the sky-high ownership fees. I would not be surprised to see this launch in the UK as a plastic version. Hope I’m wrong as it will probably force Amex to up its game.

Introduction to Loops

A simple script for displaying how loops work.

i = 0

numbers = []

while i < 8:
	print "At the top i is now %d" % i
	numbers.append(i)
	
	i = i + 1
	print "Numbers now:", numbers
	print "Number at the bottom is now: %d" % i
	
print "The numbers:"

for num in numbers:
	print num

Salary Calculator 2

Here is a slightly modified script for the Salary Calculator. This time we are writing the result to a text file. Some folks over on the Python forum helped me with target.write(str(round(total, 2)).encode()) as I could not figure a way to round the decimal place correctly.

# -*- encoding: utf-8 -*-

from sys import argv
script, answer = argv

def salary(weeks, payments):
	return (weeks * payments)

weeks = (float(raw_input("Weeks: ")))
payments = (float(raw_input("Payments: ")))

total = salary(weeks, payments)

target = open(answer, 'w')
target.truncate()

target.write(str(round(total, 2)).encode())

target.close()

Salary Calculator

This script uses quite a few new things including a function. It calculates two user input values and then gives an answer depending on the outcome. The user is asked for the number of weeks and the payment each week.

# -*- encoding: utf-8 -*-

def salary(weeks, payments):
	return (weeks * payments)

weeks = (float(raw_input("Weeks: ")))
payments = (float(raw_input("Payments: ")))

total = salary(weeks, payments)

print "\nThe total is {0:.2f}".format (total)

if total < 7999 or total == 7999:
	print "That's not good enough.\n"
	
else:
	print "You are on target.\n"

The script also uses float and format for currencies and values that use decimal places. Don’t forget to declare -*- encoding: utf-8 -*- at the beginning of the script.

Data Length

These few lines of code are useful to calculate the size of a file. Later, we’ll combine it with another script.

from sys import argv
script, filename = argv

a1 = open(filename)
data = a1.read()

print "The size of the file is %r bytes." % len (data)

Condensing

In the last script, I mentioned about condensing the lines down. It’s actually very simple to do. Just insert a semi-colon between lines.

For example:

from sys import argv script, filename becomes from sys import argv;script, filename

If you apply this in your scripts, things become much more manageable to read. Here is the previous script with the new additions.

from sys import argv;script, file_name = argv

print "Hello. let's erase the contents of the file called: '%s'." % file_name
print "If you do not want this, hit CTRL-C."

raw_input("?")

print "Opening file..."

target = open(file_name, 'w');target.truncate()

print "Contents now erased."

line1 = raw_input("Line 1: ");line2 = raw_input("Line 2: ");line3 = raw_input("Line 3: ")

print "Writing three lines..."

target.write(line1);target.write("\n");target.write(line2);target.write("\n");target.write(line3);target.write("\n")

print "Done.";print "Let's close the file."

target.close()

print "All finished."

As you can see, most of the time is saved with the part where the script asks for raw_input and when using target.write.

Erasing and Writing to a Text File

This looks quite complicated but that’s only because a lot of the lines can be condensed. The script opens the file, erases the contents and then allows the user to write in new data. Used with other scripts, it’s quite a powerful few lines of code.

from sys import argv

script, filename = argv

print "We are going to erase %r." % filename
print "If you don't want that, press ctrl-c."
print "Otherwise, hit Return."

raw_input("?")

print "Opening the file..."
target = open(filename, 'w')

print "Truncating the file...Goodbye"
target.truncate()

print "Now I am going to ask you for three lines."

line1 = raw_input("Line 1")
line2 = raw_input("Line 2")
line3 = raw_input("line 3")

print "I am going to write these to the file."

target.write(line1)
target.write("\n")

target.write(line2)
target.write("\n")

target.write(line3)
target.write("\n")

print "And finally, we close it."
target.close()

Reading a Simple Text File with Python

Here’s a script to read the contents of a text file.

from sys import argv

script, filename = argv

#open the file and read contents
txt = open(filename)
print txt.read()

print "Read the file again?"
file_again = raw_input("> ")
txt_again = open(file_again)
print txt_again.read()

Prompting, Unpacking and Variables

Remember that you need to call the script from the command line and then list the things you want to show.

So for instance, if the script is called ‘ex12.py’, then you would type ‘python ex12.py apples strawberries pears’.

The results will then be printed out as:

The script is called: ex12.py

Your first variable is: apples

Your second variable is: strawberries

Your third variable is: pears

Anyway, here is the script.

from sys import argv

script, first, second, third = argv

print "\n"

print "The script is called:", script
print "\n"
print "Your first variable is:", first
print "\n"
print "Your second variable is:", second
print "\n"
print "Your third variable is:", third

print "\n"

Fahrenheit Calculator

Simple script that calculates degrees Fahrenheit.

# -*- coding: utf-8 -*-

x = float(raw_input("°C: "))

fahrenheit = x * 1.8 + 32

print "Fahrenheit: {0:.1f}°F".format (fahrenheit)