def true_vs_pred(y_true, y_pred, train_test_ID, scale='linear', color=
    'dodgerblue', rect=(0, 0, 1, 1)):
    """
    plot y_true vs. y_pred as a scatter plot
    
    Arguments:
    ----------
        y_true, y_pred: true & pred values
        train_test_ID: string. label to be appended to axis labels 'y_true' & 'y_pred'
        scale: 'linear' or 'log' scale to be used in the plot
        color: color to be used for the data points in the plot
        rect = tight_layout(rect=...) coordinates for plot size
    """
    import matplotlib.pyplot as plt
    fig, ax = plt.subplots(1, 1)
    ax.plot(y_true, y_pred, 'o', color=color)
    ax.set_xlabel('y_true ' + train_test_ID)
    ax.set_ylabel('y_pred ' + train_test_ID)
    ax.set_xscale(scale)
    ax.set_yscale(scale)
    fig.tight_layout(rect=rect)
    plt.show()
