TheAlgorithms/Python · error · ValueError

{color} is not a valid color for multiplier band

Error message

{color} is not a valid color for multiplier band

What it means

Thrown by get_multiplier() in electronics/resistor_color_code.py when color is not a key of multiplier_color_values. The multiplier band accepts the ten digit colors plus Gold (0.1) and Silver (0.01), so any other name (Ivory, Aqua, ...) is rejected. Casing must match the table exactly.

Source

Thrown at electronics/resistor_color_code.py:177

def get_multiplier(color: str) -> float:
    """
    Function returns the multiplier value associated with the color.
    Function takes color as input and returns multiplier value

    >>> get_multiplier('Gold')
    0.1

    >>> get_multiplier('Ivory')
    Traceback (most recent call last):
      ...
    ValueError: Ivory is not a valid color for multiplier band

    """
    if color not in multiplier_color_values:
        msg = f"{color} is not a valid color for multiplier band"
        raise ValueError(msg)
    return multiplier_color_values[color]


def get_tolerance(color: str) -> float:
    """
    Function returns the tolerance value associated with the color.
    Function takes color as input and returns tolerance value.

    >>> get_tolerance('Green')
    0.5

    >>> get_tolerance('Indigo')
    Traceback (most recent call last):
      ...
    ValueError: Indigo is not a valid color for tolerance band

    """
    if color not in tolerance_color_values:

View on GitHub (pinned to f5988cc097)

Solutions

1. Use a color from the multiplier table, e.g. get_multiplier('Gold') -> 0.1 or get_multiplier('Red') -> 100.0.
2. Validate membership against the table keys (or a copied list of them) before calling.
3. Canonicalize user input: strip whitespace, title-case, and map spelling variants to the library's names.

Example fix

# before
get_multiplier('Ivory')  # ValueError

# after
get_multiplier('Gold')   # 0.1
get_multiplier('Orange') # 1000.0

MULTIPLIER_COLORS = {'Black','Brown','Red','Orange','Yellow','Green','Blue','Violet','Grey','White','Gold','Silver'}
if color not in MULTIPLIER_COLORS:
    raise ValueError(f'{color!r} is not a multiplier-band color')

def is_multiplier_color(color: str) -> bool:
    return color in multiplier_color_values

try:
    m = get_multiplier(color)
except ValueError as exc:
    # unknown color name; fall back to prompting the user again
    ...

When it happens

Trigger: get_multiplier('Ivory'); get_multiplier('gold') if the table keys are capitalized; passing a color that is only valid for tolerance or temperature-coefficient bands.

Common situations: Free-text color input from users or a UI color picker using CSS/X11 names; sending the whole band list where the tolerance color ends up in the multiplier slot; spelling variants (Grey/Gray) not matching the table keys.

Related errors

• {color} is not a valid color for significant figure bands
• {color} is not a valid color for tolerance band
• {color} is not a valid color for temperature coeffecient ban
• {total_number_of_bands} is not a valid number of bands
• {type_of_band} is not valid for a {total_number_of_bands} ba

AI-assisted analysis of TheAlgorithms/Python@f5988cc097 (2026-08-14). Data as JSON: /api/errors/b23a53d84de5c76d. Report an issue: GitHub.