def calculate_frequency_of_symbols_from_text(text):
    """Finds unique symbols in the text and calculates their frequency

    Args:
        text (str): a string with symbols

    Returns:
        list: frequency of corresponding symbols
        set: unique symbols in the text
    """
    unique_symbols_in_text = set(text)  # Find each unique symbol in the text
    length_of_text = len(text)  # Store length of text to calculate frequency
    symbols_and_freqs = []  # Store probability of each symbol in text
    for symbol in unique_symbols_in_text:
        symbols_and_freqs.append([symbol, text.count(symbol)/length_of_text])

    # Sort frequencies in decreasing order
    symbols_and_freqs = sorted(symbols_and_freqs, key=lambda elem: elem[1], reverse=True)

    return symbols_and_freqs, unique_symbols_in_text