imgofai/tree.py

import matplotlib.pyplot as plt
import numpy as np
import pandas as pd
from sklearn.tree import DecisionTreeRegressor
import PIL


def img2df(img_array):
    dim0_arr = (
        np.arange(img_array.shape[0])
        .reshape((-1, 1))
        .repeat(img_array.shape[1], axis=1)
        .flatten()
    )

    dim1_arr = (
        np.arange(img_array.shape[1])
        .reshape((1, -1))
        .repeat(img_array.shape[0], axis=0)
        .flatten()
    )

    df = pd.DataFrame({"dim0": dim0_arr, "dim1": dim1_arr})

    values = img_array.reshape((img_array.shape[0] * img_array.shape[1], -1))
    for col in range(values.shape[1]):
        df[f"value{col}"] = values[:, col]

    return df


def normalize(img):
    return (img - img.min()) / (img.max() - img.min())


def df2xy(df):
    x = df[[c for c in df if c.startswith("dim")]]
    y = df[[c for c in df if c.startswith("value")]]

    if len(y.columns) == 1:
        y = y.values.reshape(-1)
    return x, y


def tree_window(
    img, add_cartesian=True, add_rotation=False, add_polar=False, depths=(2, 6)
):
    df = img2df(img)
    x_raw, y = df2xy(df)

    sets = []
    if add_cartesian:
        sets.append(x_raw)
    if add_rotation > 0:
        # rotate
        theta = np.radians(add_rotation)
        c, s = np.cos(theta), np.sin(theta)
        R = np.array(((c, -s), (s, c)))
        xr = x_raw @ R
        sets.append(xr)
    if add_polar:
        # polar
        xp = x_raw.copy()
        xp["dim0"] = np.sqrt(((x_raw - x_raw.mean()) ** 2).sum(axis=1))
        xp["dim1"] = np.arctan2(x_raw["dim1"], x_raw["dim0"])
        sets.append(xp)

    x = pd.concat(sets, axis=1)

    fig, axes = plt.subplots(ncols=len(depths) + 1, figsize=(36, 36))

    for ax, depth in zip(axes, depths):
        model = DecisionTreeRegressor(max_depth=depth)
        model.fit(x, y)
        pred = model.predict(x).reshape(img.shape)
        if len(y.shape) == 2:
            ax.imshow(pred)
        else:
            ax.imshow(pred, cmap="gray")
        ax.set_axis_off()

    if len(y.shape) == 2:
        axes[-1].imshow(img)
    else:
        axes[-1].imshow(img, cmap="gray")
    axes[-1].set_axis_off()

    return fig


def treeify(img, max_depth):
    img_array = np.array(img)
    df = img2df(img_array)
    x, y = df2xy(df)
    model = DecisionTreeRegressor(max_depth=max_depth)
    model.fit(x, y)
    pred = PIL.Image.fromarray(
        model.predict(x).reshape(img_array.shape).round().astype("uint8")
    )
    score = model.score(x, y)
    return pred, score