easy image labeling

labeler.py

import matplotlib.pyplot as plt


def point_in_circle(xp, yp, xc, yc, r):
    return (xp - xc)**2 + (yp - yc)**2 < r**2


def draw_circles(ax, centers, classes, colors):
    for i in range(centers.shape[0]):
        circle = plt.Circle((centers[i, 1], centers[i, 0]), 20, color=colors[classes[i]], fill=False)
        ax.add_patch(circle)


class Labeler(object):
    """label candidates easily"""

    @staticmethod
    def onclick(event, args):
        ax, centers, radii, classes, colors = args
        for i, center in enumerate(centers):
            incircle = point_in_circle(
                event.ydata, event.xdata, center[0], center[1], radii[i])
            if incircle:
                classes[i] = int(not classes[i])
        draw_circles(ax, centers, classes, colors)
        plt.draw()

    @classmethod
    def label(cls, image, centers, radii, classes, colors):
        fig, ax = plt.subplots(1)
        ax.imshow(image, cmap='gray')
        draw_circles(ax, centers, classes, colors)
        args = ax, centers, radii, classes, colors
        fig.canvas.mpl_connect('button_press_event', lambda event: cls.onclick(event, args))
        plt.show(block=True)
        return classes