CustomAnchorShapeGenerator.py

from typing import List, Union
from abc import ABC, abstractmethod

import numpy as np
from PIL import Image
from sklearn.datasets import make_s_curve, make_swiss_roll


class DataExpander(ABC):
    """Abstract class for data expander with different distribution."""
        
    @abstractmethod
    def expand_data(self, data: np.ndarray, size: int, **kwargs) -> np.ndarray:
        """Return the expanded data to size."""
        raise NotImplementedError
    
    @abstractmethod
    def available_data(self, data: np.ndarray, **kwargs) -> np.ndarray:
        """Return the available data."""
        raise NotImplementedError


class AnchorExpander(DataExpander):
    """Class for anchor expander with different distribution.
    
    Args:
        expand_type (str): expand type of the anchor distribution. Options include `duplicate` or `uniform` or `gauss`. Default: 'duplicate'.
    """
    
    def __init__(self, expand_type: str = 'duplicate'):
        self.expand_type = expand_type
        self.type_map = {
            'duplicate': self.duplicate,
            'uniform': self.uniform,
            'gauss': self.gauss,
        }

    def _get_anchor_number(self, anchors: np.ndarray):
        """Return the number of anchors."""
        assert anchors.ndim == 2 , "anchors should be 2D array."
        assert anchors.shape[1] == 2 or anchors.shape[1] == 4, "each anchor shaped as (cx, cy) or (cx, cy, w, h)."
        return anchors.shape[0]
    
    def expand_data(self, data: np.ndarray, size: int, **kwargs) -> np.ndarray:
        """Return the expanded data to size."""
        anchor_num = self._get_anchor_number(data) + 1
        expand_space = np.linspace(0, size, anchor_num).astype(int)
        expand_num = expand_space[1:] - expand_space[:-1]
        
        return self.type_map[self.expand_type](data, expand_num)
    
    def available_data(self, data: np.ndarray, type=np.float32, **kwargs) -> np.ndarray:
        """Return the available anchors ranged [0, 1] with type."""
        data[:, 0::2] = np.clip(data[:, 0::2], 0, 1)
        data[:, 1::2] = np.clip(data[:, 1::2], 0, 1)
        if data.dtype != type:
            data = data.astype(type)
        return data
    
    def duplicate(self, anchors: np.ndarray, expand_num: np.ndarray):
        """Duplicate each anchor form anchors to expand_num."""
        return anchors.repeat(expand_num, axis=0)
        
    def uniform(self, anchors: np.ndarray, expand_num: np.ndarray):
        """Uniformly expand each anchor form anchors to expand_num in anchor region."""
        assert anchors.shape[1] == 4, "Uniformly expand only support anchors shaped as (cx, cy, w, h)."
        new_anchors = []
        for n, (cx, cy, w, h) in zip(expand_num, anchors):
            lt = [cx - w / 2, cy - h / 2]
            rb = [cx + w / 2, cy + h / 2]
            new_anchors.append(np.random.uniform(lt, rb, (n, 2)))
        return np.concatenate(new_anchors, axis=0)
        
    def gauss(self, anchors: np.ndarray, expand_num: np.ndarray):
        """Gaussian expand each anchor form anchors to expand_num in anchor region."""
        assert anchors.shape[1] == 4, "Gaussian expand only support anchors shaped as (cx, cy, w, h)."
        new_anchors = []
        for n, (cx, cy, w, h) in zip(expand_num, anchors):
            new_anchors.append(np.random.multivariate_normal([cx, cy], [[w, 0], [0, h]], n))
        return np.concatenate(new_anchors, axis=0)


class DataDistributor(ABC):
    """Abstract class for data distributor."""
    
    @abstractmethod
    def get_distribution(self, data: np.ndarray, **kwargs):
        """Return the data distribution."""
        raise NotImplementedError


class AnchorDistributor(DataDistributor, AnchorExpander):
    """Abstract class for anchor distributor.
    
    Args:
        width (int): width of the distribution.
        height (int): height of the distribution.
        depth (int): depth of the distribution. Default: 1.
        expand_type (str): type of the anchor distribution. Options include `duplicate` or `uniform` or `gauss`. Default: 'duplicate'.
    """
    
    def __init__(self, width: int, height: int, depth: int = 1, 
                 expand_type: str = 'duplicate'):
        self.width = width
        self.height = height
        self.depth = depth
        AnchorExpander.__init__(self, expand_type)
    
    @property
    def dis_point_num(self):
        """Return the number of expanded distribution points."""
        return int(self.width * self.height)
    
    def get_distribution(self, data: np.ndarray, type: str = '1d',  **kwargs):
        """Return the anchor distribution."""
        if type == '1d':
            return self.to_1d_distribution(data)
        elif type == 'img':
            return self.to_img_distribution(data)
        else:
            raise ValueError(f"Unsupported distribute type {type}.")
    
    def to_1d_distribution(self, anchors: np.ndarray):
        """Return the 1D distribution of anchors shaped [NxD, *]."""
        anchors = np.repeat(anchors, self.depth, axis=0)
        return anchors
    
    def to_img_distribution(self, anchors: np.ndarray) -> Image.Image:
        """Return the Image filled distribution of anchors."""
        assert self.depth == 1 or self.depth == 3, "Only support depth 1 (GRAY) or 3(RGB)."
        img = filled_anchors(anchors, self.width, self.height)
        gray_img = Image.fromarray(img)
        if self.depth == 1:
            return gray_img
        else:
            return gray_img.convert('RGB')


def filled_anchors(anchors: np.ndarray, width: int, height: int) -> np.ndarray:
    """Return the hist filled in distributed anchors' c_xy along (x,y) shaped [W, H]."""
    assert anchors.ndim == 2, "anchors should be 2D array."
    assert anchors.max() <= 1 and anchors.min() >= 0, "anchors should be ranged [0, 1]."
    
    anchor_cxcy = (anchors[:, :2] * np.array([width-1, height-1])).astype(int)
    anchor_unique, anchor_counts = np.unique(anchor_cxcy, axis=0, return_counts=True)
    anchor_counts = anchor_counts * 255.0 / anchor_counts.max()
    anchor_counts = anchor_counts.astype(int).clip(0, 255)
    anchor_index = anchor_unique[:, 1], anchor_unique[:, 0]
    hist = np.zeros((width, height), dtype=np.uint8)
    hist[anchor_index] = anchor_counts
    return hist


class CustomAnchorShape(AnchorDistributor):
    """Custom anchor shape distributor.
    
    Args:
        width (int): width of the distribution.
        height (int): height of the distribution.
        depth (int): depth of the distribution. Default: 1.
        custom_data (List[Union[np.ndarray, str]]): custom data to be added to the sample. Include `s_curve`, `swiss_roll` and `custom_anchor`.
        custom_anchor_combination (bool): whether to combine custom anchors.
        custom_anchor_relative_coord (bool): whether the custom anchor is relative coordinate.
        expand_type (str): how to expand the anchor. Options include `duplicate` or `uniform` or `gauss`. Default: 'duplicate'.
    """

    def __init__(self, width: int, height: int, 
                 depth: int = 1, 
                 custom_data: List[Union[np.ndarray, str]] = [],
                 custom_anchor_combination: bool = False,
                 custom_anchor_relative_coord: bool = True,
                 expand_type: str = 'duplicate',):
        AnchorDistributor.__init__(self, width, height, depth, expand_type)
        self.custom_anchor_combination = custom_anchor_combination
        self.custom_anchor_relative_coord = custom_anchor_relative_coord
        self.custom_shapes = [data for data in custom_data if isinstance(data, str)]
        self.custom_anchors = [data for data in custom_data if isinstance(data, (np.ndarray, list, tuple))]
        
    @property
    def custom_shapes(self):
        return self._custom_shapes
    
    @custom_shapes.setter
    def custom_shapes(self, value: List[str]):
        shapes = []
        for shape in value:
            assert isinstance(shape, str), "Custom shape must be str."
            shapes.append(self._get_spical_shape(shape))
        self._custom_shapes = shapes
        
    @property
    def custom_anchors(self):
        return self._custom_anchors
    
    @custom_anchors.setter
    def custom_anchors(self, value: List[np.ndarray]):
        anchors = []
        for anchor in value:
            if isinstance(anchor, (list, tuple)):
                if not isinstance(anchor[0], (list, tuple)):
                    anchor = [anchor]
                anchor = np.array(anchor)
            assert isinstance(anchor, np.ndarray), "Custom anchor must be np.ndarray."
            anchors.append(anchor)
        self._custom_anchors = self._get_anchor_combinations(anchors)
        
    @property
    def custom_data(self):
        return self.custom_shapes + self.custom_anchors
        
    def _get_spical_shape(self, shape_name: str, type=np.float32) -> np.ndarray:
        """Get special shape data shaped [N, 2]. Range [0, 1]"""
        if shape_name == 's_curve':
            shape = make_s_curve(self.dis_point_num, noise=0.1)[0]
            shape = shape[:, [0, 2]]
        elif shape_name == 'swiss_roll':
            shape = make_swiss_roll(self.dis_point_num, noise=0.5)[0]
            shape = shape[:, [0, 2]]
        else:
            raise ValueError(f"Not supported shape {shape_name}. Only support 's_curve' or 'swiss_roll'.")
        shape[:, 0] = (shape[:, 0] - shape[:, 0].min())  / (shape[:, 0].max() - shape[:, 0].min())
        shape[:, 1] = (shape[:, 1] - shape[:, 1].min()) / (shape[:, 1].max() - shape[:, 1].min())
        return shape.astype(type)
    
    def _pad_custom_anchor(self, anchor:np.ndarray):
        """Pad custom anchor num to `self.dis_point_num`."""
        if not self.custom_anchor_relative_coord:
            anchor = anchor / np.array([self.width, self.height])
        anchor = self.expand_data(anchor, self.dis_point_num)
        return self.available_data(anchor)
    
    def _get_anchor_combinations(self, anchors: np.ndarray) -> np.ndarray:
        """Get combinations of anchors shaped [C(N, 1)+...+C(N, N), N, 2]."""
        comb_anchors = []
        if self.custom_anchor_combination:
            from itertools import combinations
            index = np.arange(len(anchors))
            for r in index:
                for comb_i in combinations(index, r+1):
                    comb = np.concatenate([anchors[i] for i in comb_i], axis=0)
                    comb_anchors.append(self._pad_custom_anchor(comb))
        else:
            for anchor in anchors:
                comb_anchors.append(self._pad_custom_anchor(anchor))
        return comb_anchors