1AKIFT POS Test (Group B)

2025-01-23

Max. 100 points

Name:

Task	Max.	Achieved
1	50
2	50
Sum	100

Grading: >= 88: 1, >=76: 2, >=64 : 3, >50: 4, <=50: 5

50 points
When doing electronics projects you have to work with resistors. Resistors are small. If you printed the resistance value on them, it would be hard to read. To get around this problem, color-coded bands are printed on the resistors to denote their resistance values.
The following colors correspond to the values of the first two rings:
black: 0, brown: 1, red: 2, orange: 3, yellow: 4, green: 5, blue: 6, violet: 7, grey: 8, white: 9
To represent the number 33 on a resistor, two orange rings would be used. The third ring represents the order of magnitude of the resistance value. A black ring indicates that the result of the first two rings has to be multiplied by 1. A brown ring indicates multiplication by 10. Red indicates multiplication by 100 and so forth.
Write a function generate_colors(resistance: int) -> list[str] that takes a desired resistance value and returns a list of colors to be printed. For example:
```
>>> generate_colors(330)
['orange', 'orange', 'brown']
>>> generate_colors(8200)
['grey', 'red', 'red']
```
Use function annotations and a docstring including a doctest to receive full points.
5 points for correct signature including type annotations
5 points for a proper doctest
10 points for representing the color value mapping
5 points for creating a list to hold the resulting colors
5 points for each correct color name
5 points for appending the colors to the list
5 points for returning the result
```
values = [  # value corresponds to index of color
    "black", "brown", "red", "orange", "yellow", "green", "blue", "violet",
    "grey", "white"]

def generate_colors(resistance: int) -> list[str]:
    """
    Generate the colors on a resistor given its resistance.

    >>> generate_colors(330)
    ['orange', 'orange', 'brown']
    """
    colors = []
    resistance = str(resistance)
    colors.append(values[int(resistance[0])])
    colors.append(values[int(resistance[1])])
    colors.append(values[len(resistance[2:])])
    return colors
```

50 points
Your function generate_colors(.) above solves the manufacturer's problem of printing the correct colors. Now, it is your duty to solve the hobbyist's problem of de-coding the colors into a human readable resistance value. Implement a function decode_resistance(colors: list[str]) -> str that takes a list of colors and returns the decoded resistance. Note that the resulting resistance has to be represented as a string including the proper unit using a metric prefix whenever appropriate. For example:

>>> decode_resistance(['orange', 'orange', 'brown'])
'330 ohms'
>>> decode_resistance(['grey', 'red', 'red'])
'8.2 kiloohms'
>>> decode_resistance(['grey', 'red', 'blue'])
'82.0 megaohms'

Use function annotations and a docstring including a doctest to receive full points.

5 points for correct signature including type annotations
5 points for a proper doctest
5 points for representing the color value mapping
5 points for translating the colors to values
5 points for calculating the correct total value
5 points for each correct unit
5 points for returning the resulting string

values = [  # value corresponds to index of color
    "black", "brown", "red", "orange", "yellow", "green", "blue", "violet",
    "grey", "white"]

def decode_resistance(colors: list[str]) -> str:
    """
    Return a resistance value in ohms given its color bands.

    >>> decode_resistance(['grey', 'red', 'red'])
    '8.2 kiloohms'
    """
    base_value = values.index(colors[0]) * 10 + values.index(colors[1])
    value = base_value * 10 ** values.index(colors[2])
    unit = "ohms"
    if value // 10 ** 9:
        unit = "gigaohms"
        value /= 10 ** 9
    elif value // 10 ** 6:
        unit = "megaohms"
        value /= 10 ** 6
    elif value // 10 ** 3:
        unit = "kiloohms"
        value /= 10 ** 3
    return f'{value} {unit}'