oopdawg/summer-work

summer work 2023

summer-work

These are coding projects done during the summer of 2023. This also includes coding files for the edx AP CSA course.

In progress: baseConverter (java and python), Uno score tracker app

summer-work's Issues

No hardcoded values when they are meaningful and spread: 2 and 36 should be refactored as constants like MIN_BASE and MAX_BASE

summer-work/java/BaseConverter.java

Lines 73 to 81 in 34e2efe

	if (startBase < 2 || startBase > 36){
	throw new IllegalArgumentException("Invalid start base: " + startBase);
	}
	// invalid end bases
	else if (endBase < 2 || endBase > 36){
	throw new IllegalArgumentException("Invalid end base: " + endBase);
	}

get() already returns null in Java is key is not present. Also, to test key presence, should use containsKey() method

summer-work/java/BaseConverter.java

Line 84 in 34e2efe

if (digitToValue.getOrDefault(s, null) == null){

No comprehension for strings, but the equivalent is to use the join function against an empty string ''.join(...)

summer-work/python/baseConverter.py

Lines 33 to 36 in 34e2efe

	output = ''
	for i in endDigits:
	output += valueToDigit[i]

HashMap are always the same whatever the BaseConverter instance we use. Turn them static

summer-work/java/BaseConverter.java

Lines 14 to 35 in 34e2efe

	// adds digits 0 to 9
	for (int i = 0; i < 10; i++){
	digitToValue.put(Integer.toString(i), i);
	valueToDigit.put(i, Integer.toString(i));
	}
	// adds letters A to Z
	int value = 0;
	for (char c = 'A'; c <= 'Z'; c++){ // c cycles through all the letters with ASCII values
	value = 10 + (c - 'A'); // Calculates value using ASCII values. The +10 is because 0 through 9 is already mapped to the digits
	digitToValue.put(Character.toString(c), value);
	valueToDigit.put(value, Character.toString(c));
	}
	}
	// Dictionary to get character digits to int value
	// eg A = 10
	HashMap<String, Integer> digitToValue = new HashMap<>();
	// Dictionary to get int value to digits
	HashMap<Integer, String> valueToDigit = new HashMap<>();

The initialization code in the constructor should be then moved to a static initializer block

Digits variable used once so not necessary

summer-work/python/baseConverter.py

Line 19 in 34e2efe

for e, digit in enumerate(digits):

This is enough as it's used once only:
for e, digit in enumerate(reversed(num)):

This is built. in the int() function

summer-work/python/baseConverter.py

Line 20 in 3b9d820

numBase10 += digitToValue[digit]*startBase**e

Python variables style is snake_case (python...) not camelCase like Java

https://github.com/Oopdawg/summer-work/blob/34e2efe32685ecefd567a7ea01d132df29257e3b/python/baseConverter.py

The inputs are not validated so a user could enter anything they want

summer-work/python/baseConverter.py

Lines 1 to 4 in 34e2efe

	num = (input("Enter a number: ")).upper()
	startBase = int(input("Enter starting base: "))
	endBase = int(input("Enter ending base: "))

Use list comprehension and dict.update instead

summer-work/python/baseConverter.py

Lines 5 to 10 in 34e2efe

	digitToValue = {}
	for i in range(0, 10):
	digitToValue[str(i)] = i
	for ascii in range(ord('A'), ord('Z')+1):
	digitToValue[chr(ascii)] = ascii-ord('A')+10

Exceptions are not handled, if inputs are invalid, the program will crash here

summer-work/java/BaseConverter.java

Line 94 in 34e2efe

converter.validateInputs();

Avoid copy paste of code outside of while loop

summer-work/python/baseConverter.py

Lines 22 to 30 in 34e2efe

	endDigits = []
	quotient = numBase10//endBase
	remainder = numBase10%endBase
	endDigits.append(remainder)
	while quotient != 0:
	remainder = quotient%endBase
	quotient //= endBase
	endDigits.append(remainder)

With a bit of logic, no need to copy code and run it once out of the loop.
Goal is to run the loop at list once, whatever the quotient value to begin with.
This is true is the endDigits is empty, so we can test for that:

endDigits = []
quotient = numBase10

while quotient or not endDigits:
    quotient, remainder = divmod(quotient, endBase)
    endDigits.append(remainder)

Alternative writing

summer-work/python/baseConverter.py

Lines 14 to 15 in 34e2efe

	digits = [c for c in num]
	digits.reverse()

reverse is fine to reverse the sequence. however, as the list was just built, an alternative is to create the list out of the sequence already in the right order:

num[::-1] # returns the sequence in reverse. num = '123' will return '321'

list(sequence) create a list which each element from the sequence. An str is a sequence and each element is a char.

so list(num[::-1]) give the same result.

To be a bit more readable, 'reversed' is a built-in function reversing the sequence order

list(reversed('123')) works too

Rewrite algorithm with that base

# TODO D2 rewrite algorithm with that base

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