def conv_value_rgb(value, colormap, norm):
    """
    Normalizes values in a vector and transforms it into corresponding
    hex color using given colormap
    :param value: numpy vector from dataframe apply function with expression
    values
    :param colormap: matplotlib colormap object
    :param norm: matplotlib Normalize or LogNorm object
    :return: returns hex colors in vector format
    """
    return value.apply(norm).apply(colormap)